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-rw-r--r--src/misc/realpath.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/src/misc/realpath.c b/src/misc/realpath.c
index f6b55495..8dcf5ec9 100644
--- a/src/misc/realpath.c
+++ b/src/misc/realpath.c
@@ -1,6 +1,49 @@
#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
char *realpath(const char *filename, char *resolved)
{
+ int fd;
+ ssize_t r;
+ struct stat st1, st2;
+ char buf[15+3*sizeof(int)];
+ int alloc = 0;
+
+ if (!filename) {
+ errno = EINVAL;
+ return 0;
+ }
+
+ if (!resolved) {
+ alloc = 1;
+ resolved = malloc(PATH_MAX);
+ if (!resolved) return 0;
+ }
+
+ fd = open(filename, O_RDONLY|O_NONBLOCK);
+ if (fd < 0) return 0;
+ snprintf(buf, sizeof buf, "/proc/self/fd/%d", fd);
+
+ r = readlink(buf, resolved, PATH_MAX-1);
+ if (r < 0) goto err;
+ resolved[r] = 0;
+
+ fstat(fd, &st1);
+ r = stat(resolved, &st2);
+ if (r<0 || st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino) {
+ if (!r) errno = ELOOP;
+ goto err;
+ }
+
+ close(fd);
+ return resolved;
+err:
+ if (alloc) free(resolved);
+ close(fd);
return 0;
}