tempfile.c: introduce 'create_tempfile_mode'

In the next patch, 'hold_lock_file_for_update' will gain an additional 'mode' parameter to specify permissions for the associated temporary file. Since the lockfile.c machinery uses 'create_tempfile' which always creates a temporary file with global read-write permissions, introduce a variant here that allows specifying the mode. Note that the mode given to 'create_tempfile_mode' is not guaranteed to be written to disk, since it is subject to both the umask and 'core.sharedRepository'. Arguably, all temporary files should have permission 0444, since they are likely to be renamed into place and then not written to again. This is a much larger change than we may want to take on in this otherwise small patch, so for the time being, make 'create_tempfile' behave as it has always done by inlining it to 'create_tempfile_mode' with mode set to '0666'. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Taylor Blau committed Apr 27, 2020 at 10:27 UTC bef0413c3595acb469cc212792c12b7106048ddc

2 files changed +12 -4

tempfile.c

+3 -3

@@ -130,17 +130,17 @@ static void deactivate_tempfile(struct tempfile *tempfile)

130 }

131

132 /* Make sure errno contains a meaningful value on error */

133 -struct tempfile *create_tempfile(const char *path)

133 +struct tempfile *create_tempfile_mode(const char *path, int mode)

134 {

135 struct tempfile *tempfile = new_tempfile();

136

137 strbuf_add_absolute_path(&tempfile->filename, path);

138 tempfile->fd = open(tempfile->filename.buf,

139 - O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0666);

139 + O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, mode);

140 if (O_CLOEXEC && tempfile->fd < 0 && errno == EINVAL)

141 /* Try again w/o O_CLOEXEC: the kernel might not support it */

142 tempfile->fd = open(tempfile->filename.buf,

143 - O_RDWR | O_CREAT | O_EXCL, 0666);

143 + O_RDWR | O_CREAT | O_EXCL, mode);

144 if (tempfile->fd < 0) {

145 deactivate_tempfile(tempfile);

146 return NULL;

tempfile.h

+9 -1

@@ -88,8 +88,16 @@ struct tempfile {

88 * Attempt to create a temporary file at the specified `path`. Return

89 * a tempfile (whose "fd" member can be used for writing to it), or

90 * NULL on error. It is an error if a file already exists at that path.

91 + * Note that `mode` will be further modified by the umask, and possibly

92 + * `core.sharedRepository`, so it is not guaranteed to have the given

93 + * mode.

94 */

92 -struct tempfile *create_tempfile(const char *path);

95 +struct tempfile *create_tempfile_mode(const char *path, int mode);

96 +

97 +static inline struct tempfile *create_tempfile(const char *path)

98 +{

99 + return create_tempfile_mode(path, 0666);

100 +}

101

102 /*

103 * Register an existing file as a tempfile, meaning that it will be