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authorTomas Volf <~@wolfsden.cz>2024-08-10 00:54:30 +0200
committerLudovic Courtès <ludo@gnu.org>2024-10-20 21:22:23 +0200
commit0ceb0036c3a2efdd8d5b0da0c68d15b67fe24689 (patch)
tree26ac1e5144973f4bcaca38511f65a418dbdb8735
parent21e3e1c420ace116961ecdf0001c289c28fa73c6 (diff)
downloadguile-0ceb0036c3a2efdd8d5b0da0c68d15b67fe24689.tar.gz
filesys.c: Fix readlink for ports on Darwin.
When passed a port, `readlink' relies on the Linux specific behavior of empty c_path meaning "the fd itself". That does not work on Darwin. Since there is no branch that would yield both fd and c_path, fallback to freadlink when __APPLE__ is defined. * libguile/filesys.c (do_readlink): Call freadlink for !__APPLE__. * configure.ac (AC_CHECK_FUNCS): Add freadlink. Signed-off-by: Ludovic Courtès <ludo@gnu.org>
-rw-r--r--configure.ac2
-rw-r--r--libguile/filesys.c13
2 files changed, 12 insertions, 3 deletions
diff --git a/configure.ac b/configure.ac
index ce3ae0226..af9176b46 100644
--- a/configure.ac
+++ b/configure.ac
@@ -556,7 +556,7 @@ AC_CHECK_FUNCS([DINFINITY DQNAN cexp chsize clog clog10 ctermid \
fstatat futimens openat \
sched_getaffinity sched_setaffinity sendfile pipe2 \
posix_spawn_file_actions_addclosefrom_np \
- clearenv])
+ clearenv freadlink])
# The newlib C library uses _NL_ prefixed locale langinfo constants.
AC_CHECK_DECLS([_NL_NUMERIC_GROUPING], [], [], [[#include <langinfo.h>]])
diff --git a/libguile/filesys.c b/libguile/filesys.c
index 8657fedc3..6896e00ea 100644
--- a/libguile/filesys.c
+++ b/libguile/filesys.c
@@ -1192,14 +1192,23 @@ SCM_DEFINE (scm_symlinkat, "symlinkat", 3, 0, 0,
#undef FUNC_NAME
#endif /* HAVE_SYMLINKAT */
-/* Static helper function for choosing between readlink
+/* Static helper function for choosing between readlink, freadlink,
and readlinkat. */
static int
do_readlink (int fd, const char *c_path, char *buf, size_t size)
{
-#ifdef HAVE_READLINKAT
+/* Darwin does not accept empty c_path. */
+#if HAVE_READLINKAT && !__APPLE__
if (fd != -1)
return readlinkat (fd, c_path, buf, size);
+#elif HAVE_FREADLINK
+ /* There is no branch in s_scm_readlink that would lead to having both
+ FD and non-empty C_PATH. Therefore if FD is set, we (on Darwin
+ only) use freadlink and ignore C_PATH. On Linux this case is
+ already handled by readlinkat, but Darwin does not understand empty
+ C_PATH to mean "the fd itself" the way Linux does. */
+ if (fd != -1)
+ return freadlink (fd, buf, size);
#else
(void) fd;
#endif