util: when creating temporary file names, allow including extra id string in it

This adds a "char *extra" parameter to tempfn_xxxxxx(), tempfn_random(),
tempfn_ranomd_child(). If non-NULL this string is included in the middle
of the newly created file name. This is useful for being able to
distuingish the kind of temporary file when we see one.

This also adds tests for the three call.

For now, we don't make use of this at all, but port all users over.

1 files changed, 25 insertions, 16 deletions

diff --git a/src/basic/util.c b/src/basic/util.c
index 6f6906f877..b7c70af541 100644
--- a/src/basic/util.c
+++ b/src/basic/util.c
@@ -2521,7 +2521,7 @@ int fopen_temporary(const char *path, FILE **_f, char **_temp_path) {
         assert(_f);
         assert(_temp_path);
 
-        r = tempfn_xxxxxx(path, &t);
+        r = tempfn_xxxxxx(path, NULL, &t);
         if (r < 0)
                 return r;
 
@@ -2551,7 +2551,7 @@ int symlink_atomic(const char *from, const char *to) {
         assert(from);
         assert(to);
 
-        r = tempfn_random(to, &t);
+        r = tempfn_random(to, NULL, &t);
         if (r < 0)
                 return r;
 
@@ -2594,7 +2594,7 @@ int mknod_atomic(const char *path, mode_t mode, dev_t dev) {
 
         assert(path);
 
-        r = tempfn_random(path, &t);
+        r = tempfn_random(path, NULL, &t);
         if (r < 0)
                 return r;
 
@@ -2615,7 +2615,7 @@ int mkfifo_atomic(const char *path, mode_t mode) {
 
         assert(path);
 
-        r = tempfn_random(path, &t);
+        r = tempfn_random(path, NULL, &t);
         if (r < 0)
                 return r;
 
@@ -4969,7 +4969,7 @@ int fflush_and_check(FILE *f) {
         return 0;
 }
 
-int tempfn_xxxxxx(const char *p, char **ret) {
+int tempfn_xxxxxx(const char *p, const char *extra, char **ret) {
         const char *fn;
         char *t;
 
@@ -4981,24 +4981,27 @@ int tempfn_xxxxxx(const char *p, char **ret) {
          *         /foo/bar/waldo
          *
          * Into this:
-         *         /foo/bar/.#waldoXXXXXX
+         *         /foo/bar/.#<extra>waldoXXXXXX
          */
 
         fn = basename(p);
         if (!filename_is_valid(fn))
                 return -EINVAL;
 
-        t = new(char, strlen(p) + 2 + 6 + 1);
+        if (extra == NULL)
+                extra = "";
+
+        t = new(char, strlen(p) + 2 + strlen(extra) + 6 + 1);
         if (!t)
                 return -ENOMEM;
 
-        strcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), fn), "XXXXXX");
+        strcpy(stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn), "XXXXXX");
 
         *ret = path_kill_slashes(t);
         return 0;
 }
 
-int tempfn_random(const char *p, char **ret) {
+int tempfn_random(const char *p, const char *extra, char **ret) {
         const char *fn;
         char *t, *x;
         uint64_t u;
@@ -5012,18 +5015,21 @@ int tempfn_random(const char *p, char **ret) {
          *         /foo/bar/waldo
          *
          * Into this:
-         *         /foo/bar/.#waldobaa2a261115984a9
+         *         /foo/bar/.#<extra>waldobaa2a261115984a9
          */
 
         fn = basename(p);
         if (!filename_is_valid(fn))
                 return -EINVAL;
 
-        t = new(char, strlen(p) + 2 + 16 + 1);
+        if (!extra)
+                extra = "";
+
+        t = new(char, strlen(p) + 2 + strlen(extra) + 16 + 1);
         if (!t)
                 return -ENOMEM;
 
-        x = stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), fn);
+        x = stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn);
 
         u = random_u64();
         for (i = 0; i < 16; i++) {
@@ -5037,7 +5043,7 @@ int tempfn_random(const char *p, char **ret) {
         return 0;
 }
 
-int tempfn_random_child(const char *p, char **ret) {
+int tempfn_random_child(const char *p, const char *extra, char **ret) {
         char *t, *x;
         uint64_t u;
         unsigned i;
@@ -5048,14 +5054,17 @@ int tempfn_random_child(const char *p, char **ret) {
         /* Turns this:
          *         /foo/bar/waldo
          * Into this:
-         *         /foo/bar/waldo/.#3c2b6219aa75d7d0
+         *         /foo/bar/waldo/.#<extra>3c2b6219aa75d7d0
          */
 
-        t = new(char, strlen(p) + 3 + 16 + 1);
+        if (!extra)
+                extra = "";
+
+        t = new(char, strlen(p) + 3 + strlen(extra) + 16 + 1);
         if (!t)
                 return -ENOMEM;
 
-        x = stpcpy(stpcpy(t, p), "/.#");
+        x = stpcpy(stpcpy(stpcpy(t, p), "/.#"), extra);
 
         u = random_u64();
         for (i = 0; i < 16; i++) {