perf_counter tools: add in basic glue from Git

First very raw version at having a central 'perf' command and
a list of subcommands:

  perf top
  perf stat
  perf record
  perf report
  ...

This is done by picking up Git's collection of utility functions,
and hacking them to build fine in this new environment.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 966 insertions, 0 deletions

diff --git a/Documentation/perf_counter/config.c b/Documentation/perf_counter/config.c
new file mode 100644
index 000000000000..672d53959334
--- /dev/null
+++ b/Documentation/perf_counter/config.c
@@ -0,0 +1,966 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) Linus Torvalds, 2005
+ * Copyright (C) Johannes Schindelin, 2005
+ *
+ */
+#include "util.h"
+#include "cache.h"
+#include "exec_cmd.h"
+
+#define MAXNAME (256)
+
+static FILE *config_file;
+static const char *config_file_name;
+static int config_linenr;
+static int config_file_eof;
+static int zlib_compression_seen;
+
+const char *config_exclusive_filename = NULL;
+
+static int get_next_char(void)
+{
+        int c;
+        FILE *f;
+
+        c = '\n';
+        if ((f = config_file) != NULL) {
+                c = fgetc(f);
+                if (c == '\r') {
+                        /* DOS like systems */
+                        c = fgetc(f);
+                        if (c != '\n') {
+                                ungetc(c, f);
+                                c = '\r';
+                        }
+                }
+                if (c == '\n')
+                        config_linenr++;
+                if (c == EOF) {
+                        config_file_eof = 1;
+                        c = '\n';
+                }
+        }
+        return c;
+}
+
+static char *parse_value(void)
+{
+        static char value[1024];
+        int quote = 0, comment = 0, len = 0, space = 0;
+
+        for (;;) {
+                int c = get_next_char();
+                if (len >= sizeof(value) - 1)
+                        return NULL;
+                if (c == '\n') {
+                        if (quote)
+                                return NULL;
+                        value[len] = 0;
+                        return value;
+                }
+                if (comment)
+                        continue;
+                if (isspace(c) && !quote) {
+                        space = 1;
+                        continue;
+                }
+                if (!quote) {
+                        if (c == ';' || c == '#') {
+                                comment = 1;
+                                continue;
+                        }
+                }
+                if (space) {
+                        if (len)
+                                value[len++] = ' ';
+                        space = 0;
+                }
+                if (c == '\\') {
+                        c = get_next_char();
+                        switch (c) {
+                        case '\n':
+                                continue;
+                        case 't':
+                                c = '\t';
+                                break;
+                        case 'b':
+                                c = '\b';
+                                break;
+                        case 'n':
+                                c = '\n';
+                                break;
+                        /* Some characters escape as themselves */
+                        case '\\': case '"':
+                                break;
+                        /* Reject unknown escape sequences */
+                        default:
+                                return NULL;
+                        }
+                        value[len++] = c;
+                        continue;
+                }
+                if (c == '"') {
+                        quote = 1-quote;
+                        continue;
+                }
+                value[len++] = c;
+        }
+}
+
+static inline int iskeychar(int c)
+{
+        return isalnum(c) || c == '-';
+}
+
+static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
+{
+        int c;
+        char *value;
+
+        /* Get the full name */
+        for (;;) {
+                c = get_next_char();
+                if (config_file_eof)
+                        break;
+                if (!iskeychar(c))
+                        break;
+                name[len++] = tolower(c);
+                if (len >= MAXNAME)
+                        return -1;
+        }
+        name[len] = 0;
+        while (c == ' ' || c == '\t')
+                c = get_next_char();
+
+        value = NULL;
+        if (c != '\n') {
+                if (c != '=')
+                        return -1;
+                value = parse_value();
+                if (!value)
+                        return -1;
+        }
+        return fn(name, value, data);
+}
+
+static int get_extended_base_var(char *name, int baselen, int c)
+{
+        do {
+                if (c == '\n')
+                        return -1;
+                c = get_next_char();
+        } while (isspace(c));
+
+        /* We require the format to be '[base "extension"]' */
+        if (c != '"')
+                return -1;
+        name[baselen++] = '.';
+
+        for (;;) {
+                int c = get_next_char();
+                if (c == '\n')
+                        return -1;
+                if (c == '"')
+                        break;
+                if (c == '\\') {
+                        c = get_next_char();
+                        if (c == '\n')
+                                return -1;
+                }
+                name[baselen++] = c;
+                if (baselen > MAXNAME / 2)
+                        return -1;
+        }
+
+        /* Final ']' */
+        if (get_next_char() != ']')
+                return -1;
+        return baselen;
+}
+
+static int get_base_var(char *name)
+{
+        int baselen = 0;
+
+        for (;;) {
+                int c = get_next_char();
+                if (config_file_eof)
+                        return -1;
+                if (c == ']')
+                        return baselen;
+                if (isspace(c))
+                        return get_extended_base_var(name, baselen, c);
+                if (!iskeychar(c) && c != '.')
+                        return -1;
+                if (baselen > MAXNAME / 2)
+                        return -1;
+                name[baselen++] = tolower(c);
+        }
+}
+
+static int perf_parse_file(config_fn_t fn, void *data)
+{
+        int comment = 0;
+        int baselen = 0;
+        static char var[MAXNAME];
+
+        /* U+FEFF Byte Order Mark in UTF8 */
+        static const unsigned char *utf8_bom = (unsigned char *) "\xef\xbb\xbf";
+        const unsigned char *bomptr = utf8_bom;
+
+        for (;;) {
+                int c = get_next_char();
+                if (bomptr && *bomptr) {
+                        /* We are at the file beginning; skip UTF8-encoded BOM
+                         * if present. Sane editors won't put this in on their
+                         * own, but e.g. Windows Notepad will do it happily. */
+                        if ((unsigned char) c == *bomptr) {
+                                bomptr++;
+                                continue;
+                        } else {
+                                /* Do not tolerate partial BOM. */
+                                if (bomptr != utf8_bom)
+                                        break;
+                                /* No BOM at file beginning. Cool. */
+                                bomptr = NULL;
+                        }
+                }
+                if (c == '\n') {
+                        if (config_file_eof)
+                                return 0;
+                        comment = 0;
+                        continue;
+                }
+                if (comment || isspace(c))
+                        continue;
+                if (c == '#' || c == ';') {
+                        comment = 1;
+                        continue;
+                }
+                if (c == '[') {
+                        baselen = get_base_var(var);
+                        if (baselen <= 0)
+                                break;
+                        var[baselen++] = '.';
+                        var[baselen] = 0;
+                        continue;
+                }
+                if (!isalpha(c))
+                        break;
+                var[baselen] = tolower(c);
+                if (get_value(fn, data, var, baselen+1) < 0)
+                        break;
+        }
+        die("bad config file line %d in %s", config_linenr, config_file_name);
+}
+
+static int parse_unit_factor(const char *end, unsigned long *val)
+{
+        if (!*end)
+                return 1;
+        else if (!strcasecmp(end, "k")) {
+                *val *= 1024;
+                return 1;
+        }
+        else if (!strcasecmp(end, "m")) {
+                *val *= 1024 * 1024;
+                return 1;
+        }
+        else if (!strcasecmp(end, "g")) {
+                *val *= 1024 * 1024 * 1024;
+                return 1;
+        }
+        return 0;
+}
+
+static int perf_parse_long(const char *value, long *ret)
+{
+        if (value && *value) {
+                char *end;
+                long val = strtol(value, &end, 0);
+                unsigned long factor = 1;
+                if (!parse_unit_factor(end, &factor))
+                        return 0;
+                *ret = val * factor;
+                return 1;
+        }
+        return 0;
+}
+
+int perf_parse_ulong(const char *value, unsigned long *ret)
+{
+        if (value && *value) {
+                char *end;
+                unsigned long val = strtoul(value, &end, 0);
+                if (!parse_unit_factor(end, &val))
+                        return 0;
+                *ret = val;
+                return 1;
+        }
+        return 0;
+}
+
+static void die_bad_config(const char *name)
+{
+        if (config_file_name)
+                die("bad config value for '%s' in %s", name, config_file_name);
+        die("bad config value for '%s'", name);
+}
+
+int perf_config_int(const char *name, const char *value)
+{
+        long ret = 0;
+        if (!perf_parse_long(value, &ret))
+                die_bad_config(name);
+        return ret;
+}
+
+unsigned long perf_config_ulong(const char *name, const char *value)
+{
+        unsigned long ret;
+        if (!perf_parse_ulong(value, &ret))
+                die_bad_config(name);
+        return ret;
+}
+
+int perf_config_bool_or_int(const char *name, const char *value, int *is_bool)
+{
+        *is_bool = 1;
+        if (!value)
+                return 1;
+        if (!*value)
+                return 0;
+        if (!strcasecmp(value, "true") || !strcasecmp(value, "yes") || !strcasecmp(value, "on"))
+                return 1;
+        if (!strcasecmp(value, "false") || !strcasecmp(value, "no") || !strcasecmp(value, "off"))
+                return 0;
+        *is_bool = 0;
+        return perf_config_int(name, value);
+}
+
+int perf_config_bool(const char *name, const char *value)
+{
+        int discard;
+        return !!perf_config_bool_or_int(name, value, &discard);
+}
+
+int perf_config_string(const char **dest, const char *var, const char *value)
+{
+        if (!value)
+                return config_error_nonbool(var);
+        *dest = strdup(value);
+        return 0;
+}
+
+static int perf_default_core_config(const char *var, const char *value)
+{
+        /* Add other config variables here and to Documentation/config.txt. */
+        return 0;
+}
+
+int perf_default_config(const char *var, const char *value, void *dummy)
+{
+        if (!prefixcmp(var, "core."))
+                return perf_default_core_config(var, value);
+
+        /* Add other config variables here and to Documentation/config.txt. */
+        return 0;
+}
+
+int perf_config_from_file(config_fn_t fn, const char *filename, void *data)
+{
+        int ret;
+        FILE *f = fopen(filename, "r");
+
+        ret = -1;
+        if (f) {
+                config_file = f;
+                config_file_name = filename;
+                config_linenr = 1;
+                config_file_eof = 0;
+                ret = perf_parse_file(fn, data);
+                fclose(f);
+                config_file_name = NULL;
+        }
+        return ret;
+}
+
+const char *perf_etc_perfconfig(void)
+{
+        static const char *system_wide;
+        if (!system_wide)
+                system_wide = system_path(ETC_PERFCONFIG);
+        return system_wide;
+}
+
+static int perf_env_bool(const char *k, int def)
+{
+        const char *v = getenv(k);
+        return v ? perf_config_bool(k, v) : def;
+}
+
+int perf_config_system(void)
+{
+        return !perf_env_bool("PERF_CONFIG_NOSYSTEM", 0);
+}
+
+int perf_config_global(void)
+{
+        return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
+}
+
+int perf_config(config_fn_t fn, void *data)
+{
+        int ret = 0, found = 0;
+        char *repo_config = NULL;
+        const char *home = NULL;
+
+        /* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
+        if (config_exclusive_filename)
+                return perf_config_from_file(fn, config_exclusive_filename, data);
+        if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
+                ret += perf_config_from_file(fn, perf_etc_perfconfig(),
+                                            data);
+                found += 1;
+        }
+
+        home = getenv("HOME");
+        if (perf_config_global() && home) {
+                char *user_config = strdup(mkpath("%s/.perfconfig", home));
+                if (!access(user_config, R_OK)) {
+                        ret += perf_config_from_file(fn, user_config, data);
+                        found += 1;
+                }
+                free(user_config);
+        }
+
+        repo_config = perf_pathdup("config");
+        if (!access(repo_config, R_OK)) {
+                ret += perf_config_from_file(fn, repo_config, data);
+                found += 1;
+        }
+        free(repo_config);
+        if (found == 0)
+                return -1;
+        return ret;
+}
+
+/*
+ * Find all the stuff for perf_config_set() below.
+ */
+
+#define MAX_MATCHES 512
+
+static struct {
+        int baselen;
+        char* key;
+        int do_not_match;
+        regex_t* value_regex;
+        int multi_replace;
+        size_t offset[MAX_MATCHES];
+        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
+        int seen;
+} store;
+
+static int matches(const char* key, const char* value)
+{
+        return !strcmp(key, store.key) &&
+                (store.value_regex == NULL ||
+                 (store.do_not_match ^
+                  !regexec(store.value_regex, value, 0, NULL, 0)));
+}
+
+static int store_aux(const char* key, const char* value, void *cb)
+{
+        const char *ep;
+        size_t section_len;
+
+        switch (store.state) {
+        case KEY_SEEN:
+                if (matches(key, value)) {
+                        if (store.seen == 1 && store.multi_replace == 0) {
+                                warning("%s has multiple values", key);
+                        } else if (store.seen >= MAX_MATCHES) {
+                                error("too many matches for %s", key);
+                                return 1;
+                        }
+
+                        store.offset[store.seen] = ftell(config_file);
+                        store.seen++;
+                }
+                break;
+        case SECTION_SEEN:
+                /*
+                 * What we are looking for is in store.key (both
+                 * section and var), and its section part is baselen
+                 * long.  We found key (again, both section and var).
+                 * We would want to know if this key is in the same
+                 * section as what we are looking for.  We already
+                 * know we are in the same section as what should
+                 * hold store.key.
+                 */
+                ep = strrchr(key, '.');
+                section_len = ep - key;
+
+                if ((section_len != store.baselen) ||
+                    memcmp(key, store.key, section_len+1)) {
+                        store.state = SECTION_END_SEEN;
+                        break;
+                }
+
+                /*
+                 * Do not increment matches: this is no match, but we
+                 * just made sure we are in the desired section.
+                 */
+                store.offset[store.seen] = ftell(config_file);
+                /* fallthru */
+        case SECTION_END_SEEN:
+        case START:
+                if (matches(key, value)) {
+                        store.offset[store.seen] = ftell(config_file);
+                        store.state = KEY_SEEN;
+                        store.seen++;
+                } else {
+                        if (strrchr(key, '.') - key == store.baselen &&
+                              !strncmp(key, store.key, store.baselen)) {
+                                        store.state = SECTION_SEEN;
+                                        store.offset[store.seen] = ftell(config_file);
+                        }
+                }
+        }
+        return 0;
+}
+
+static int write_error(const char *filename)
+{
+        error("failed to write new configuration file %s", filename);
+
+        /* Same error code as "failed to rename". */
+        return 4;
+}
+
+static int store_write_section(int fd, const char* key)
+{
+        const char *dot;
+        int i, success;
+        struct strbuf sb = STRBUF_INIT;
+
+        dot = memchr(key, '.', store.baselen);
+        if (dot) {
+                strbuf_addf(&sb, "[%.*s \"", (int)(dot - key), key);
+                for (i = dot - key + 1; i < store.baselen; i++) {
+                        if (key[i] == '"' || key[i] == '\\')
+                                strbuf_addch(&sb, '\\');
+                        strbuf_addch(&sb, key[i]);
+                }
+                strbuf_addstr(&sb, "\"]\n");
+        } else {
+                strbuf_addf(&sb, "[%.*s]\n", store.baselen, key);
+        }
+
+        success = write_in_full(fd, sb.buf, sb.len) == sb.len;
+        strbuf_release(&sb);
+
+        return success;
+}
+
+static int store_write_pair(int fd, const char* key, const char* value)
+{
+        int i, success;
+        int length = strlen(key + store.baselen + 1);
+        const char *quote = "";
+        struct strbuf sb = STRBUF_INIT;
+
+        /*
+         * Check to see if the value needs to be surrounded with a dq pair.
+         * Note that problematic characters are always backslash-quoted; this
+         * check is about not losing leading or trailing SP and strings that
+         * follow beginning-of-comment characters (i.e. ';' and '#') by the
+         * configuration parser.
+         */
+        if (value[0] == ' ')
+                quote = "\"";
+        for (i = 0; value[i]; i++)
+                if (value[i] == ';' || value[i] == '#')
+                        quote = "\"";
+        if (i && value[i - 1] == ' ')
+                quote = "\"";
+
+        strbuf_addf(&sb, "\t%.*s = %s",
+                    length, key + store.baselen + 1, quote);
+
+        for (i = 0; value[i]; i++)
+                switch (value[i]) {
+                case '\n':
+                        strbuf_addstr(&sb, "\\n");
+                        break;
+                case '\t':
+                        strbuf_addstr(&sb, "\\t");
+                        break;
+                case '"':
+                case '\\':
+                        strbuf_addch(&sb, '\\');
+                default:
+                        strbuf_addch(&sb, value[i]);
+                        break;
+                }
+        strbuf_addf(&sb, "%s\n", quote);
+
+        success = write_in_full(fd, sb.buf, sb.len) == sb.len;
+        strbuf_release(&sb);
+
+        return success;
+}
+
+static ssize_t find_beginning_of_line(const char* contents, size_t size,
+        size_t offset_, int* found_bracket)
+{
+        size_t equal_offset = size, bracket_offset = size;
+        ssize_t offset;
+
+contline:
+        for (offset = offset_-2; offset > 0
+                        && contents[offset] != '\n'; offset--)
+                switch (contents[offset]) {
+                        case '=': equal_offset = offset; break;
+                        case ']': bracket_offset = offset; break;
+                }
+        if (offset > 0 && contents[offset-1] == '\\') {
+                offset_ = offset;
+                goto contline;
+        }
+        if (bracket_offset < equal_offset) {
+                *found_bracket = 1;
+                offset = bracket_offset+1;
+        } else
+                offset++;
+
+        return offset;
+}
+
+int perf_config_set(const char* key, const char* value)
+{
+        return perf_config_set_multivar(key, value, NULL, 0);
+}
+
+/*
+ * If value==NULL, unset in (remove from) config,
+ * if value_regex!=NULL, disregard key/value pairs where value does not match.
+ * if multi_replace==0, nothing, or only one matching key/value is replaced,
+ *     else all matching key/values (regardless how many) are removed,
+ *     before the new pair is written.
+ *
+ * Returns 0 on success.
+ *
+ * This function does this:
+ *
+ * - it locks the config file by creating ".perf/config.lock"
+ *
+ * - it then parses the config using store_aux() as validator to find
+ *   the position on the key/value pair to replace. If it is to be unset,
+ *   it must be found exactly once.
+ *
+ * - the config file is mmap()ed and the part before the match (if any) is
+ *   written to the lock file, then the changed part and the rest.
+ *
+ * - the config file is removed and the lock file rename()d to it.
+ *
+ */
+int perf_config_set_multivar(const char* key, const char* value,
+        const char* value_regex, int multi_replace)
+{
+        int i, dot;
+        int fd = -1, in_fd;
+        int ret;
+        char* config_filename;
+        const char* last_dot = strrchr(key, '.');
+
+        if (config_exclusive_filename)
+                config_filename = strdup(config_exclusive_filename);
+        else
+                config_filename = perf_pathdup("config");
+
+        /*
+         * Since "key" actually contains the section name and the real
+         * key name separated by a dot, we have to know where the dot is.
+         */
+
+        if (last_dot == NULL) {
+                error("key does not contain a section: %s", key);
+                ret = 2;
+                goto out_free;
+        }
+        store.baselen = last_dot - key;
+
+        store.multi_replace = multi_replace;
+
+        /*
+         * Validate the key and while at it, lower case it for matching.
+         */
+        store.key = malloc(strlen(key) + 1);
+        dot = 0;
+        for (i = 0; key[i]; i++) {
+                unsigned char c = key[i];
+                if (c == '.')
+                        dot = 1;
+                /* Leave the extended basename untouched.. */
+                if (!dot || i > store.baselen) {
+                        if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
+                                error("invalid key: %s", key);
+                                free(store.key);
+                                ret = 1;
+                                goto out_free;
+                        }
+                        c = tolower(c);
+                } else if (c == '\n') {
+                        error("invalid key (newline): %s", key);
+                        free(store.key);
+                        ret = 1;
+                        goto out_free;
+                }
+                store.key[i] = c;
+        }
+        store.key[i] = 0;
+
+        /*
+         * If .perf/config does not exist yet, write a minimal version.
+         */
+        in_fd = open(config_filename, O_RDONLY);
+        if ( in_fd < 0 ) {
+                free(store.key);
+
+                if ( ENOENT != errno ) {
+                        error("opening %s: %s", config_filename,
+                              strerror(errno));
+                        ret = 3; /* same as "invalid config file" */
+                        goto out_free;
+                }
+                /* if nothing to unset, error out */
+                if (value == NULL) {
+                        ret = 5;
+                        goto out_free;
+                }
+
+                store.key = (char*)key;
+                if (!store_write_section(fd, key) ||
+                    !store_write_pair(fd, key, value))
+                        goto write_err_out;
+        } else {
+                struct stat st;
+                char* contents;
+                size_t contents_sz, copy_begin, copy_end;
+                int i, new_line = 0;
+
+                if (value_regex == NULL)
+                        store.value_regex = NULL;
+                else {
+                        if (value_regex[0] == '!') {
+                                store.do_not_match = 1;
+                                value_regex++;
+                        } else
+                                store.do_not_match = 0;
+
+                        store.value_regex = (regex_t*)malloc(sizeof(regex_t));
+                        if (regcomp(store.value_regex, value_regex,
+                                        REG_EXTENDED)) {
+                                error("invalid pattern: %s", value_regex);
+                                free(store.value_regex);
+                                ret = 6;
+                                goto out_free;
+                        }
+                }
+
+                store.offset[0] = 0;
+                store.state = START;
+                store.seen = 0;
+
+                /*
+                 * After this, store.offset will contain the *end* offset
+                 * of the last match, or remain at 0 if no match was found.
+                 * As a side effect, we make sure to transform only a valid
+                 * existing config file.
+                 */
+                if (perf_config_from_file(store_aux, config_filename, NULL)) {
+                        error("invalid config file %s", config_filename);
+                        free(store.key);
+                        if (store.value_regex != NULL) {
+                                regfree(store.value_regex);
+                                free(store.value_regex);
+                        }
+                        ret = 3;
+                        goto out_free;
+                }
+
+                free(store.key);
+                if (store.value_regex != NULL) {
+                        regfree(store.value_regex);
+                        free(store.value_regex);
+                }
+
+                /* if nothing to unset, or too many matches, error out */
+                if ((store.seen == 0 && value == NULL) ||
+                                (store.seen > 1 && multi_replace == 0)) {
+                        ret = 5;
+                        goto out_free;
+                }
+
+                fstat(in_fd, &st);
+                contents_sz = xsize_t(st.st_size);
+                contents = mmap(NULL, contents_sz, PROT_READ,
+                        MAP_PRIVATE, in_fd, 0);
+                close(in_fd);
+
+                if (store.seen == 0)
+                        store.seen = 1;
+
+                for (i = 0, copy_begin = 0; i < store.seen; i++) {
+                        if (store.offset[i] == 0) {
+                                store.offset[i] = copy_end = contents_sz;
+                        } else if (store.state != KEY_SEEN) {
+                                copy_end = store.offset[i];
+                        } else
+                                copy_end = find_beginning_of_line(
+                                        contents, contents_sz,
+                                        store.offset[i]-2, &new_line);
+
+                        if (copy_end > 0 && contents[copy_end-1] != '\n')
+                                new_line = 1;
+
+                        /* write the first part of the config */
+                        if (copy_end > copy_begin) {
+                                if (write_in_full(fd, contents + copy_begin,
+                                                  copy_end - copy_begin) <
+                                    copy_end - copy_begin)
+                                        goto write_err_out;
+                                if (new_line &&
+                                    write_in_full(fd, "\n", 1) != 1)
+                                        goto write_err_out;
+                        }
+                        copy_begin = store.offset[i];
+                }
+
+                /* write the pair (value == NULL means unset) */
+                if (value != NULL) {
+                        if (store.state == START) {
+                                if (!store_write_section(fd, key))
+                                        goto write_err_out;
+                        }
+                        if (!store_write_pair(fd, key, value))
+                                goto write_err_out;
+                }
+
+                /* write the rest of the config */
+                if (copy_begin < contents_sz)
+                        if (write_in_full(fd, contents + copy_begin,
+                                          contents_sz - copy_begin) <
+                            contents_sz - copy_begin)
+                                goto write_err_out;
+
+                munmap(contents, contents_sz);
+        }
+
+        ret = 0;
+
+out_free:
+        free(config_filename);
+        return ret;
+
+write_err_out:
+        goto out_free;
+
+}
+
+static int section_name_match (const char *buf, const char *name)
+{
+        int i = 0, j = 0, dot = 0;
+        for (; buf[i] && buf[i] != ']'; i++) {
+                if (!dot && isspace(buf[i])) {
+                        dot = 1;
+                        if (name[j++] != '.')
+                                break;
+                        for (i++; isspace(buf[i]); i++)
+                                ; /* do nothing */
+                        if (buf[i] != '"')
+                                break;
+                        continue;
+                }
+                if (buf[i] == '\\' && dot)
+                        i++;
+                else if (buf[i] == '"' && dot) {
+                        for (i++; isspace(buf[i]); i++)
+                                ; /* do_nothing */
+                        break;
+                }
+                if (buf[i] != name[j++])
+                        break;
+        }
+        return (buf[i] == ']' && name[j] == 0);
+}
+
+/* if new_name == NULL, the section is removed instead */
+int perf_config_rename_section(const char *old_name, const char *new_name)
+{
+        int ret = 0, remove = 0;
+        char *config_filename;
+        int out_fd;
+        char buf[1024];
+
+        if (config_exclusive_filename)
+                config_filename = strdup(config_exclusive_filename);
+        else
+                config_filename = perf_pathdup("config");
+        if (out_fd < 0) {
+                ret = error("could not lock config file %s", config_filename);
+                goto out;
+        }
+
+        if (!(config_file = fopen(config_filename, "rb"))) {
+                /* no config file means nothing to rename, no error */
+                goto unlock_and_out;
+        }
+
+        while (fgets(buf, sizeof(buf), config_file)) {
+                int i;
+                int length;
+                for (i = 0; buf[i] && isspace(buf[i]); i++)
+                        ; /* do nothing */
+                if (buf[i] == '[') {
+                        /* it's a section */
+                        if (section_name_match (&buf[i+1], old_name)) {
+                                ret++;
+                                if (new_name == NULL) {
+                                        remove = 1;
+                                        continue;
+                                }
+                                store.baselen = strlen(new_name);
+                                if (!store_write_section(out_fd, new_name)) {
+                                        goto out;
+                                }
+                                continue;
+                        }
+                        remove = 0;
+                }
+                if (remove)
+                        continue;
+                length = strlen(buf);
+                if (write_in_full(out_fd, buf, length) != length) {
+                        goto out;
+                }
+        }
+        fclose(config_file);
+ unlock_and_out:
+ out:
+        free(config_filename);
+        return ret;
+}
+
+/*
+ * Call this to report error for your variable that should not
+ * get a boolean value (i.e. "[my] var" means "true").
+ */
+int config_error_nonbool(const char *var)
+{
+        return error("Missing value for '%s'", var);
+}