relocatable-prog: fix link error

[gnulib.git] / lib / careadlinkat.c

diff --git a/lib/careadlinkat.c b/lib/careadlinkat.c
index 5f0d43c..751578b 100644 (file)
--- a/lib/careadlinkat.c
+++ b/lib/careadlinkat.c
@@ -18,13 +18,10 @@
 
 /* Written by Paul Eggert, Bruno Haible, and Jim Meyering.  */
 
-#define _GL_USE_STDLIB_ALLOC 1
 #include <config.h>
 
 #include "careadlinkat.h"
 
-#include "allocator.h"
-
 #include <errno.h>
 #include <limits.h>
 #include <stdlib.h>
@@ -40,23 +37,21 @@
 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
 #endif
 
-#if ! HAVE_READLINKAT
-/* Ignore FD.  Get the symbolic link value of FILENAME and put it into
-   BUFFER, with size BUFFER_SIZE.  This function acts like readlink
-   but has readlinkat's signature.  */
+#include "allocator.h"
+
+/* Get the symbolic link value of FILENAME and put it into BUFFER, with
+   size BUFFER_SIZE.  This function acts like readlink  but has
+   readlinkat's signature.  */
 ssize_t
 careadlinkatcwd (int fd, char const *filename, char *buffer,
                  size_t buffer_size)
 {
-  (void) fd;
+  /* FD must be AT_FDCWD here, otherwise the caller is using this
+     function in contexts for which it was not meant for.  */
+  if (fd != AT_FDCWD)
+    abort ();
   return readlink (filename, buffer, buffer_size);
 }
-#endif
-
-/* A standard allocator.  For now, only careadlinkat needs this, but
-   perhaps it should be moved to the allocator module.  */
-static struct allocator const standard_allocator =
-  { malloc, realloc, free, NULL };
 
 /* Assuming the current directory is FD, get the symbolic link value
    of FILENAME as a null-terminated string and put it into a buffer.
@@ -72,7 +67,10 @@ static struct allocator const standard_allocator =
    the returned value if it is nonnull and is not BUFFER.  A null
    ALLOC stands for the standard allocator.
 
-   The PREADLINKAT function specifies how to read links.
+   The PREADLINKAT function specifies how to read links.  It operates
+   like POSIX readlinkat()
+   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
+   but can assume that its first argument is the same as FD.
 
    If successful, return the buffer address; otherwise return NULL and
    set errno.  */
@@ -90,7 +88,7 @@ careadlinkat (int fd, char const *filename,
   char stack_buf[1024];
 
   if (! alloc)
-    alloc = &standard_allocator;
+    alloc = &stdlib_allocator;
 
   if (! buffer_size)
     {
@@ -135,6 +133,7 @@ careadlinkat (int fd, char const *filename,
           if (buf == stack_buf)
             {
               char *b = (char *) alloc->allocate (link_size);
+              buf_size = link_size;
               if (! b)
                 break;
               memcpy (b, buf, link_size);
@@ -158,6 +157,11 @@ careadlinkat (int fd, char const *filename,
         buf_size *= 2;
       else if (buf_size < buf_size_max)
         buf_size = buf_size_max;
+      else if (buf_size_max < SIZE_MAX)
+        {
+          errno = ENAMETOOLONG;
+          return NULL;
+        }
       else
         break;
       buf = (char *) alloc->allocate (buf_size);
@@ -165,7 +169,7 @@ careadlinkat (int fd, char const *filename,
   while (buf);
 
   if (alloc->die)
-    alloc->die ();
+    alloc->die (buf_size);
   errno = ENOMEM;
   return NULL;
 }