Improve error messages when temporary file creation fails

Before, when creating a temporary file failed, a generic 'Unable to create
temporary file' message was printed. In some cases this could lead to
confusion as to which directory should be checked for correct permissions etc.

This patch adds the template for the temporary filename to the error message,
converting it to an absolute path if needed. A test verifies that the template
is indeed printed when pointing to a nonexistent or unwritable directory.

A copy of the original template is made in case mkstemp clears the template.

Signed-off-by: Arnout Engelen <arnouten@bzzt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Makefile b/Makefile
index 57d9c65e03c96d0b337298b32ccaeccaae348c8e..03a51cb8f2d4d9d63a9350e794d4ce6e463c7ee1 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -434,6 +434,7 @@ TEST_PROGRAMS_NEED_X += test-string-pool
 TEST_PROGRAMS_NEED_X += test-svn-fe
 TEST_PROGRAMS_NEED_X += test-treap
 TEST_PROGRAMS_NEED_X += test-index-version
+TEST_PROGRAMS_NEED_X += test-mktemp
 
 TEST_PROGRAMS = $(patsubst %,%$X,$(TEST_PROGRAMS_NEED_X))
 

diff --git a/t/t0070-fundamental.sh b/t/t0070-fundamental.sh
index 680d7d68612b168a2642ab64e7bc6c15c316d5b4..9bee8bfd2e063c40bae2d76930370bd9e8ba8fa5 100755 (executable)
--- a/t/t0070-fundamental.sh
+++ b/t/t0070-fundamental.sh
@@ -12,4 +12,17 @@ test_expect_success 'character classes (isspace, isalpha etc.)' '
        test-ctype
 '
 
+test_expect_success 'mktemp to nonexistent directory prints filename' '
+       test_must_fail test-mktemp doesnotexist/testXXXXXX 2>err &&
+       grep "doesnotexist/test" err
+'
+
+test_expect_success POSIXPERM 'mktemp to unwritable directory prints filename' '
+       mkdir cannotwrite &&
+       chmod -w cannotwrite &&
+       test_when_finished "chmod +w cannotwrite" &&
+       test_must_fail test-mktemp cannotwrite/testXXXXXX 2>err &&
+       grep "cannotwrite/test" err
+'
+
 test_done

diff --git a/test-mktemp.c b/test-mktemp.c
new file mode 100644 (file)
index 0000000..c8c5421
--- /dev/null
+++ b/test-mktemp.c
@@ -0,0 +1,14 @@
+/*
+ * test-mktemp.c: code to exercise the creation of temporary files
+ */
+#include "git-compat-util.h"
+
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               usage("Expected 1 parameter defining the temporary file template");
+
+       xmkstemp(xstrdup(argv[1]));
+
+       return 0;
+}

diff --git a/wrapper.c b/wrapper.c
index 8d7dd31c4ba5439652d11e5ada06e0d52bc04e4f..55b074ec46b0a222b03f8bea42f4d5cdd9811293 100644 (file)
--- a/wrapper.c
+++ b/wrapper.c
@@ -198,10 +198,22 @@ FILE *xfdopen(int fd, const char *mode)
 int xmkstemp(char *template)
 {
        int fd;
+       char origtemplate[PATH_MAX];
+       strlcpy(origtemplate, template, sizeof(origtemplate));
 
        fd = mkstemp(template);
-       if (fd < 0)
-               die_errno("Unable to create temporary file");
+       if (fd < 0) {
+               int saved_errno = errno;
+               const char *nonrelative_template;
+
+               if (!template[0])
+                       template = origtemplate;
+
+               nonrelative_template = make_nonrelative_path(template);
+               errno = saved_errno;
+               die_errno("Unable to create temporary file '%s'",
+                       nonrelative_template);
+       }
        return fd;
 }
 
@@ -321,10 +333,22 @@ int gitmkstemps(char *pattern, int suffix_len)
 int xmkstemp_mode(char *template, int mode)
 {
        int fd;
+       char origtemplate[PATH_MAX];
+       strlcpy(origtemplate, template, sizeof(origtemplate));
 
        fd = git_mkstemp_mode(template, mode);
-       if (fd < 0)
-               die_errno("Unable to create temporary file");
+       if (fd < 0) {
+               int saved_errno = errno;
+               const char *nonrelative_template;
+
+               if (!template[0])
+                       template = origtemplate;
+
+               nonrelative_template = make_nonrelative_path(template);
+               errno = saved_errno;
+               die_errno("Unable to create temporary file '%s'",
+                       nonrelative_template);
+       }
        return fd;
 }