source: npl/system/klibc/patches/implement-realpath.patch @ 5fedc40

usr/include/stdlib.h

@@ -92 +92 @@
         return 0;               /* devpts does this all for us! */
 }
 
+__extern char *realpath(const char *, char *);
+
 #endif                          /* _STDLIB_H */

usr/klibc/Kbuild

@@ -60 +60 @@
           send.o recv.o \
           access.o chmod.o chown.o dup2.o mknod.o poll.o rename.o stat.o \
           lchown.o link.o rmdir.o unlink.o utimes.o lstat.o mkdir.o \
-          readlink.o select.o symlink.o pipe.o \
+          readlink.o realpath.o select.o symlink.o pipe.o \
           ctype/isalnum.o ctype/isalpha.o ctype/isascii.o \
           ctype/isblank.o ctype/iscntrl.o ctype/isdigit.o \
           ctype/isgraph.o ctype/islower.o ctype/isprint.o \

new file usr/klibc/realpath.c

@@ +1 @@
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/*
+ * Note that this requires name to refer to an existing file.  This is
+ * correct according to POSIX.  However, BSD and GNU implementations
+ * also allow name to refer to a non-existing file in an existing
+ * directory.
+ */
+
+char *realpath(const char *name, char *resolved_name)
+{
+        static const char proc_fd_prefix[] = "/proc/self/fd/";
+        char proc_fd_name[sizeof(proc_fd_prefix) + sizeof(int) * 3];
+        int allocated = 0;
+        int fd;
+        ssize_t len;
+
+        /* Open for path lookup only */
+        fd = open(name, O_PATH);
+        if (fd < 0)
+                return NULL;
+
+        if (!resolved_name) {
+                resolved_name = malloc(PATH_MAX);
+                if (!resolved_name)
+                        goto out_close;
+                allocated = 1;
+        }
+
+        /* Use procfs to read back the resolved name */
+        sprintf(proc_fd_name, "%s%d", proc_fd_prefix, fd);
+        len = readlink(proc_fd_name, resolved_name, PATH_MAX - 1);
+        if (len < 0) {
+                if (allocated)
+                        free(resolved_name);
+                resolved_name = NULL;
+        } else {
+                resolved_name[len] = 0;
+        }
+
+out_close:
+        close(fd);
+        return resolved_name;
+}