fixdep: use malloc() and read() to load dep_file to buffer

Commit dee81e988674 ("fixdep: faster CONFIG_ search") changed how to
read files in which CONFIG options are searched.  It used malloc()
and read() instead of mmap() because it needed to zero-terminate the
buffer in order to use strstr().  print_deps() was left untouched
since there was no reason to change it.

Now, I have two motivations to change it in the same way.

 - do_config_file() and print_deps() do quite similar things; they
   open a file, load it onto memory, and pass it to a parser function.
   If we use malloc() and read() for print_deps() too, we can factor
   out the common code.  (I will do this in the next commit.)

 - parse_dep_file() copies each token to a temporary buffer because
   it needs to zero-terminate it to be passed to printf().  It is not
   possible to modify the buffer directly because it is mmap'ed with
   O_RDONLY.  If we load the file content into a malloc'ed buffer, we
   can insert '\0' after each token, and save memcpy().  (I will do
   this in the commit after next.)

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

1 files changed, 32 insertions, 24 deletions

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index b9b4bbf4e8dd..91bb4c13f121 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -104,7 +104,6 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <sys/mman.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <string.h>
@@ -308,24 +307,27 @@ static void do_config_file(const char *filename)
  * assignments are parsed not only by make, but also by the rather simple
  * parser in scripts/mod/sumversion.c.
  */
-static void parse_dep_file(void *map, size_t len)
+static void parse_dep_file(char *m)
 {
-        char *m = map;
-        char *end = m + len;
         char *p;
         char s[PATH_MAX];
-        int is_target;
+        int is_last, is_target;
         int saw_any_target = 0;
         int is_first_dep = 0;
 
-        while (m < end) {
+        while (1) {
                 /* Skip any "white space" */
-                while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
+                while (*m == ' ' || *m == '\\' || *m == '\n')
                         m++;
+
+                if (!*m)
+                        break;
+
                 /* Find next "white space" */
                 p = m;
-                while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
+                while (*p && *p != ' ' && *p != '\\' && *p != '\n')
                         p++;
+                is_last = (*p == '\0');
                 /* Is the token we found a target name? */
                 is_target = (*(p-1) == ':');
                 /* Don't write any target names into the dependency file */
@@ -373,6 +375,10 @@ static void parse_dep_file(void *map, size_t len)
                                 do_config_file(s);
                         }
                 }
+
+                if (is_last)
+                        break;
+
                 /*
                  * Start searching for next token immediately after the first
                  * "whitespace" character that follows this token.
@@ -391,40 +397,42 @@ static void parse_dep_file(void *map, size_t len)
         printf("$(deps_%s):\n", target);
 }
 
-static void print_deps(void)
+static void print_deps(const char *filename)
 {
         struct stat st;
         int fd;
-        void *map;
+        char *buf;
 
-        fd = open(depfile, O_RDONLY);
+        fd = open(filename, O_RDONLY);
         if (fd < 0) {
                 fprintf(stderr, "fixdep: error opening depfile: ");
-                perror(depfile);
+                perror(filename);
                 exit(2);
         }
         if (fstat(fd, &st) < 0) {
                 fprintf(stderr, "fixdep: error fstat'ing depfile: ");
-                perror(depfile);
+                perror(filename);
                 exit(2);
         }
         if (st.st_size == 0) {
-                fprintf(stderr,"fixdep: %s is empty\n",depfile);
                 close(fd);
                 return;
         }
-        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-        if ((long) map == -1) {
-                perror("fixdep: mmap");
-                close(fd);
-                return;
+        buf = malloc(st.st_size + 1);
+        if (!buf) {
+                perror("fixdep: malloc");
+                exit(2);
         }
+        if (read(fd, buf, st.st_size) != st.st_size) {
+                perror("fixdep: read");
+                exit(2);
+        }
+        buf[st.st_size] = '\0';
+        close(fd);
 
-        parse_dep_file(map, st.st_size);
-
-        munmap(map, st.st_size);
+        parse_dep_file(buf);
 
-        close(fd);
+        free(buf);
 }
 
 int main(int argc, char *argv[])
@@ -440,7 +448,7 @@ int main(int argc, char *argv[])
         cmdline = argv[3];
 
         print_cmdline();
-        print_deps();
+        print_deps(depfile);
 
         return 0;
 }