Introduce a new helper function to resolve a path name, calling nbdkit_error on failure: other than doing what nbdkit_absolute_path does, it also checks that the file exists (and thus avoids errors later on). To help distinguish it from nbdkit_absolute_path, improve the documentation of the latter. Apply it where an existing path is required, both in nbdkit itself and in plugins. Related to: https://bugzilla.redhat.com/show_bug.cgi?id=1527334 --- docs/nbdkit-plugin.pod | 18 +++++++++++++++++- include/nbdkit-common.h | 1 + plugins/example2/example2.c | 2 +- plugins/file/file.c | 6 +----- plugins/gzip/gzip.c | 2 +- plugins/split/split.c | 2 +- plugins/vddk/vddk.c | 2 +- plugins/xz/xz.c | 2 +- src/plugins.c | 2 +- src/utils.c | 19 +++++++++++++++++++ 10 files changed, 44 insertions(+), 12 deletions(-) diff --git a/docs/nbdkit-plugin.pod b/docs/nbdkit-plugin.pod index 44822fc..5faba1d 100644 --- a/docs/nbdkit-plugin.pod +++ b/docs/nbdkit-plugin.pod @@ -200,13 +200,29 @@ descriptor. char *nbdkit_absolute_path (const char *filename); The utility function C<nbdkit_absolute_path> converts any path to an -absolute path. +absolute path: if it is relative, then all this function does is +prepending the current working directory to the path, with no extra +checks. If conversion was not possible, this calls C<nbdkit_error> and returns C<NULL>. Note that this function does not check that the file exists. The returned string must be freed by the caller. +=head2 C<nbdkit_realpath> + + char *nbdkit_realpath (const char *filename); + +The utility function C<nbdkit_realpath> converts any path to an +absolute path, resolving symlinks. Under the hood it uses the +C<realpath> function, and thus it fails if the path does not exist, +or it is not possible to access to any of the components of the path. + +If the path resolution was not possible, this calls C<nbdkit_error> +and returns C<NULL>. + +The returned string must be freed by the caller. + =head1 CALLBACKS =head2 C<.name> diff --git a/include/nbdkit-common.h b/include/nbdkit-common.h index 5e69579..693213f 100644 --- a/include/nbdkit-common.h +++ b/include/nbdkit-common.h @@ -60,6 +60,7 @@ extern void nbdkit_vdebug (const char *msg, va_list args); extern char *nbdkit_absolute_path (const char *path); extern int64_t nbdkit_parse_size (const char *str); extern int nbdkit_read_password (const char *value, char **password); +extern char *nbdkit_realpath (const char *path); #ifdef __cplusplus } diff --git a/plugins/example2/example2.c b/plugins/example2/example2.c index 5bc4f94..a2d6fca 100644 --- a/plugins/example2/example2.c +++ b/plugins/example2/example2.c @@ -78,7 +78,7 @@ example2_config (const char *key, const char *value) { if (strcmp (key, "file") == 0) { /* See FILENAMES AND PATHS in nbdkit-plugin(3). */ - filename = nbdkit_absolute_path (value); + filename = nbdkit_realpath (value); if (!filename) return -1; } diff --git a/plugins/file/file.c b/plugins/file/file.c index f8cb3d3..b6e33de 100644 --- a/plugins/file/file.c +++ b/plugins/file/file.c @@ -65,7 +65,7 @@ file_config (const char *key, const char *value) if (strcmp (key, "file") == 0) { /* See FILENAMES AND PATHS in nbdkit-plugin(3). */ free (filename); - filename = nbdkit_absolute_path (value); + filename = nbdkit_realpath (value); if (!filename) return -1; } @@ -90,10 +90,6 @@ file_config_complete (void) nbdkit_error ("you must supply the file=<FILENAME> parameter after the plugin name on the command line"); return -1; } - if (access (filename, F_OK) < 0) { - nbdkit_error ("access '%s': %m", filename); - return -1; - } return 0; } diff --git a/plugins/gzip/gzip.c b/plugins/gzip/gzip.c index e9dbfdb..09dd629 100644 --- a/plugins/gzip/gzip.c +++ b/plugins/gzip/gzip.c @@ -62,7 +62,7 @@ gzip_config (const char *key, const char *value) { if (strcmp (key, "file") == 0) { /* See FILENAMES AND PATHS in nbdkit-plugin(3). */ - filename = nbdkit_absolute_path (value); + filename = nbdkit_realpath (value); if (!filename) return -1; } diff --git a/plugins/split/split.c b/plugins/split/split.c index 47c366d..bdcdcf7 100644 --- a/plugins/split/split.c +++ b/plugins/split/split.c @@ -76,7 +76,7 @@ split_config (const char *key, const char *value) return -1; } filenames = new_filenames; - filenames[nr_files] = nbdkit_absolute_path (value); + filenames[nr_files] = nbdkit_realpath (value); if (filenames[nr_files] == NULL) return -1; nr_files++; diff --git a/plugins/vddk/vddk.c b/plugins/vddk/vddk.c index 1c15127..8bc1517 100644 --- a/plugins/vddk/vddk.c +++ b/plugins/vddk/vddk.c @@ -153,7 +153,7 @@ vddk_config (const char *key, const char *value) if (strcmp (key, "config") == 0) { /* See FILENAMES AND PATHS in nbdkit-plugin(3). */ free (config); - config = nbdkit_absolute_path (value); + config = nbdkit_realpath (value); if (!config) return -1; } diff --git a/plugins/xz/xz.c b/plugins/xz/xz.c index 437f798..f45e489 100644 --- a/plugins/xz/xz.c +++ b/plugins/xz/xz.c @@ -67,7 +67,7 @@ xz_config (const char *key, const char *value) { if (strcmp (key, "file") == 0) { /* See FILENAMES AND PATHS in nbdkit-plugin(3). */ - filename = nbdkit_absolute_path (value); + filename = nbdkit_realpath (value); if (!filename) return -1; } diff --git a/src/plugins.c b/src/plugins.c index dba3e24..595b632 100644 --- a/src/plugins.c +++ b/src/plugins.c @@ -134,7 +134,7 @@ plugin_dump_fields (struct backend *b) struct backend_plugin *p = container_of (b, struct backend_plugin, backend); char *path; - path = nbdkit_absolute_path (p->filename); + path = nbdkit_realpath (p->filename); printf ("path=%s\n", path); free (path); diff --git a/src/utils.c b/src/utils.c index 0083370..c6c8003 100644 --- a/src/utils.c +++ b/src/utils.c @@ -228,3 +228,22 @@ nbdkit_read_password (const char *value, char **password) return 0; } + +char * +nbdkit_realpath (const char *path) +{ + char *ret; + + if (path == NULL || *path == '\0') { + nbdkit_error ("cannot resolve a null or empty path"); + return NULL; + } + + ret = realpath (path, NULL); + if (ret == NULL) { + nbdkit_error ("realpath(%s): %m", path); + return NULL; + } + + return ret; +} -- 2.14.3