[RFC PATCH] configure: check for POSIX.1-2008 realpath(3) implementation.

diff --git a/21/ce0d8a81fa20747863ca6e2617c9a4accc040a b/21/ce0d8a81fa20747863ca6e2617c9a4accc040a
new file mode 100644 (file)
index 0000000..5b543b2
--- /dev/null
+++ b/21/ce0d8a81fa20747863ca6e2617c9a4accc040a
@@ -0,0 +1,181 @@
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+From: Tomi Ollila <tomi.ollila@iki.fi>\r
+To: notmuch@notmuchmail.org\r
+Subject: [RFC PATCH] configure: check for POSIX.1-2008 realpath(3)\r
+       implementation.\r
+Date: Sat, 25 Jan 2014 23:59:02 +0200\r
+Message-Id: <1390687142-16401-1-git-send-email-tomi.ollila@iki.fi>\r
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+Cc: tomi.ollila@iki.fi\r
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+\r
+Check whether realpath(3) supports the resolved_path == NULL feature,\r
+standardized in POSIX.1-2008.\r
+\r
+This is tested by executing the realpath(3) with NULL as second\r
+argument and the program is expected to SIGSEGV in case the\r
+feature is not supported.\r
+\r
+If the feature is not supported the compatibility code calls realpath(3)\r
+with second argument pointing to buffer with MAX_PATH in size. With\r
+this more systems are supported; those that have POSIX.1-2008 -capable\r
+realpath(3) and those that have MAX_PATH defined and realpath(3) does\r
+not exceed that limit.\r
+---\r
+\r
+I tested running configure and then make test; then make clean,\r
+edited Makefile.config POSIX_2008_REALPATH = 0 and make clean\r
+again. then tested sigsegv'ing with (memcpy(0, 0, 4)...\r
+\r
+\r
+ configure        | 32 ++++++++++++++++++++++++++++++--\r
+ notmuch-config.c | 21 ++++++++++++++++++++-\r
+ 2 files changed, 50 insertions(+), 3 deletions(-)\r
+\r
+diff --git a/configure b/configure\r
+index 13b6062..8174219 100755\r
+--- a/configure\r
++++ b/configure\r
+@@ -454,6 +454,29 @@ echo $util_byte_order\r
+ \r
+ rm -f _byteorder _byteorder.c\r
+ \r
++printf "Checking for posix 2008 realpath()... "\r
++# resolved_path == NULL is standardized in POSIX.1-2008\r
++cat > _posix_2008_realpath.c <<EOF\r
++#define _BSD_SOURCE\r
++#include <limits.h>\r
++#include <stdlib.h>\r
++#include <signal.h>\r
++void exit1(int sig) { exit(1); }\r
++int main () {\r
++ signal(SIGSEGV, exit1);\r
++ int main () { realpath (".", (char*)0); return 0;\r
++}\r
++EOF\r
++${CC} ${CFLAGS} _posix_2008_realpath.c -o _posix_2008_realpath > /dev/null 2>&1\r
++if ./_posix_2008_realpath; then\r
++      echo Yes.\r
++      posix_2008_realpath=1\r
++else\r
++      echo No.\r
++      posix_2008_realpath=0\r
++fi\r
++rm -f _posix_2008_realpath _posix_2008_realpath.c\r
++\r
+ if [ $errors -gt 0 ]; then\r
+     cat <<EOF\r
+ \r
+@@ -718,6 +741,9 @@ libdir = ${LIBDIR:=\$(prefix)/lib}\r
+ # byte order within a 32 bit word. 1234 = little, 4321 = big, 0 = guess\r
+ UTIL_BYTE_ORDER = ${util_byte_order}\r
+ \r
++# Whether realpath(3) supports resolved_path == NULL feature\r
++POSIX_2008_REALPATH = ${posix_2008_realpath}\r
++\r
+ # Whether libdir is in a path configured into ldconfig\r
+ LIBDIR_IN_LDCONFIG = ${libdir_in_ldconfig}\r
+ \r
+@@ -824,7 +850,8 @@ CONFIGURE_CFLAGS = -DHAVE_GETLINE=\$(HAVE_GETLINE) \$(GMIME_CFLAGS)      \\\r
+                  -DSTD_GETPWUID=\$(STD_GETPWUID)                       \\\r
+                  -DSTD_ASCTIME=\$(STD_ASCTIME)                         \\\r
+                  -DHAVE_XAPIAN_COMPACT=\$(HAVE_XAPIAN_COMPACT)         \\\r
+-                 -DUTIL_BYTE_ORDER=\$(UTIL_BYTE_ORDER)\r
++                 -DUTIL_BYTE_ORDER=\$(UTIL_BYTE_ORDER)                 \\\r
++                 -DPOSIX_2008_REALPATH=\$(POSIX_2008_REALPATH)\r
+ \r
+ CONFIGURE_CXXFLAGS = -DHAVE_GETLINE=\$(HAVE_GETLINE) \$(GMIME_CFLAGS)    \\\r
+                    \$(TALLOC_CFLAGS) -DHAVE_VALGRIND=\$(HAVE_VALGRIND) \\\r
+@@ -834,7 +861,8 @@ CONFIGURE_CXXFLAGS = -DHAVE_GETLINE=\$(HAVE_GETLINE) \$(GMIME_CFLAGS)    \\\r
+                    -DSTD_GETPWUID=\$(STD_GETPWUID)                     \\\r
+                    -DSTD_ASCTIME=\$(STD_ASCTIME)                       \\\r
+                    -DHAVE_XAPIAN_COMPACT=\$(HAVE_XAPIAN_COMPACT)       \\\r
+-                   -DUTIL_BYTE_ORDER=\$(UTIL_BYTE_ORDER)\r
++                   -DUTIL_BYTE_ORDER=\$(UTIL_BYTE_ORDER)               \\\r
++                   -DPOSIX_2008_REALPATH=\$(POSIX_2008_REALPATH)\r
+ \r
+ CONFIGURE_LDFLAGS =  \$(GMIME_LDFLAGS) \$(TALLOC_LDFLAGS) \$(XAPIAN_LDFLAGS)\r
+ EOF\r
+diff --git a/notmuch-config.c b/notmuch-config.c\r
+index 8d28653..14d0e5c 100644\r
+--- a/notmuch-config.c\r
++++ b/notmuch-config.c\r
+@@ -454,10 +454,26 @@ notmuch_config_save (notmuch_config_t *config)\r
+     }\r
+ \r
+     /* Try not to overwrite symlinks. */\r
++#if POSIX_2008_REALPATH\r
+     filename = realpath (config->filename, NULL);\r
++#else\r
++    /* compatibility with minor effort, not elegance, is the ruling factor\r
++       in these (two) else branches... */\r
++    char resolved_path[PATH_MAX];\r
++    filename = realpath (config->filename, resolved_path);\r
++#endif\r
+     if (! filename) {\r
+       if (errno == ENOENT) {\r
++#if POSIX_2008_REALPATH\r
+           filename = strdup (config->filename);\r
++#else\r
++          /* ... this is the other else... */\r
++          resolved_path[sizeof resolved_path - 1] = '\0';\r
++          strncpy(resolved_path, config->filename, sizeof resolved_path);\r
++          /* "faking" out of memory in case path too long -- close enough? */\r
++          filename = resolved_path[sizeof resolved_path - 1]?\r
++              resolved_path: NULL;\r
++#endif\r
+           if (! filename) {\r
+               fprintf (stderr, "Out of memory.\n");\r
+               g_free (data);\r
+@@ -480,12 +496,15 @@ notmuch_config_save (notmuch_config_t *config)\r
+                    filename, error->message);\r
+       }\r
+       g_error_free (error);\r
++#if POSIX_2008_REALPATH\r
+       free (filename);\r
++#endif\r
+       g_free (data);\r
+       return 1;\r
+     }\r
+-\r
++#if POSIX_2008_REALPATH\r
+     free (filename);\r
++#endif\r
+     g_free (data);\r
+     return 0;\r
+ }\r
+-- \r
+1.8.5.3\r
+\r