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>

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index b9b4bbf..91bb4c1 100644 (file)
--- 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;
 }