Merge pull request #26977 from poettering/find-line-startswith

add new find_line_startswith() helper

src/basic/mountpoint-util.c

@@ -125,14 +125,9 @@ static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *ret_mn
         if (r < 0)
                 return r;
 
-        p = startswith(fdinfo, "mnt_id:");
-        if (!p) {
-                p = strstr(fdinfo, "\nmnt_id:");
-                if (!p) /* The mnt_id field is a relatively new addition */
-                        return -EOPNOTSUPP;
-
-                p += 8;
-        }
+        p = find_line_startswith(fdinfo, "mnt_id:");
+        if (!p) /* The mnt_id field is a relatively new addition */
+                return -EOPNOTSUPP;
 
         p += strspn(p, WHITESPACE);
         p[strcspn(p, WHITESPACE)] = 0;

src/basic/process-util.c

@@ -1453,14 +1453,9 @@ int pidfd_get_pid(int fd, pid_t *ret) {
         if (r < 0)
                 return r;
 
-        p = startswith(fdinfo, "Pid:");
-        if (!p) {
-                p = strstr(fdinfo, "\nPid:");
-                if (!p)
-                        return -ENOTTY; /* not a pidfd? */
-
-                p += 5;
-        }
+        p = find_line_startswith(fdinfo, "Pid:");
+        if (!p)
+                return -ENOTTY; /* not a pidfd? */
 
         p += strspn(p, WHITESPACE);
         p[strcspn(p, WHITESPACE)] = 0;

src/basic/string-util.c

@@ -1260,3 +1260,26 @@ char *strdupcspn(const char *a, const char *reject) {
 
         return strndup(a, strcspn(a, reject));
 }
+
+char *find_line_startswith(const char *haystack, const char *needle) {
+        char *p;
+
+        assert(haystack);
+        assert(needle);
+
+        /* Finds the first line in 'haystack' that starts with the specified string. Returns a pointer to the
+         * first character after it */
+
+        p = strstr(haystack, needle);
+        if (!p)
+                return NULL;
+
+        if (p > haystack)
+                while (p[-1] != '\n') {
+                        p = strstr(p + 1, needle);
+                        if (!p)
+                                return NULL;
+                }
+
+        return p + strlen(needle);
+}

src/basic/string-util.h

@@ -253,3 +253,5 @@ size_t strspn_from_end(const char *str, const char *accept);
 
 char *strdupspn(const char *a, const char *accept);
 char *strdupcspn(const char *a, const char *reject);
+
+char *find_line_startswith(const char *haystack, const char *needle);

src/import/importd.c

@@ -554,9 +554,9 @@ static int manager_on_notify(sd_event_source *s, int fd, uint32_t revents, void
         };
         struct ucred *ucred;
         Manager *m = userdata;
-        char *p, *e;
         Transfer *t;
         ssize_t n;
+        char *p;
         int r;
 
         n = recvmsg_safe(fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC);
@@ -590,17 +590,11 @@ static int manager_on_notify(sd_event_source *s, int fd, uint32_t revents, void
 
         buf[n] = 0;
 
-        p = startswith(buf, "X_IMPORT_PROGRESS=");
-        if (!p) {
-                p = strstr(buf, "\nX_IMPORT_PROGRESS=");
-                if (!p)
-                        return 0;
+        p = find_line_startswith(buf, "X_IMPORT_PROGRESS=");
+        if (!p)
+                return 0;
 
-                p += 19;
-        }
-
-        e = strchrnul(p, '\n');
-        *e = 0;
+        truncate_nl(p);
 
         r = parse_percent(p);
         if (r < 0) {

src/shared/logs-show.c

@@ -93,14 +93,9 @@ static int url_from_catalog(sd_journal *j, char **ret) {
         if (r < 0)
                 return log_error_errno(r, "Failed to find catalog entry: %m");
 
-        weblink = startswith(t, "Documentation:");
-        if (!weblink) {
-                weblink = strstr(t + 1, "\nDocumentation:");
-                if (!weblink)
-                        goto notfound;
-
-                weblink += 15;
-        }
+        weblink = find_line_startswith(t, "Documentation:");
+        if (!weblink)
+                goto notfound;
 
         /* Skip whitespace to value */
         weblink += strspn(weblink, " \t");

src/test/test-string-util.c

@@ -1218,4 +1218,33 @@ TEST(make_cstring) {
         TEST_MAKE_CSTRING_ONE(test8, -EINVAL, MAKE_CSTRING_REQUIRE_TRAILING_NUL, NULL);
 }
 
+TEST(find_line_startswith) {
+        static const char text[] =
+                "foobar\n"
+                "this is a test\n"
+                "foobar: waldo\n"
+                "more\n"
+                "\n"
+                "piff\n"
+                "foobarfoobar\n"
+                "iff\n";
+        static const char emptystring[] = "";
+
+        assert_se(find_line_startswith(text, "") == text);
+        assert_se(find_line_startswith(text, "f") == text+1);
+        assert_se(find_line_startswith(text, "foobar") == text+6);
+        assert_se(!find_line_startswith(text, "foobarx"));
+        assert_se(!find_line_startswith(text, "oobar"));
+        assert_se(find_line_startswith(text, "t") == text + 8);
+        assert_se(find_line_startswith(text, "th") == text + 9);
+        assert_se(find_line_startswith(text, "this") == text + 11);
+        assert_se(find_line_startswith(text, "foobarf") == text + 54);
+        assert_se(find_line_startswith(text, "more\n") == text + 41);
+        assert_se(find_line_startswith(text, "\n") == text + 42);
+        assert_se(find_line_startswith(text, "iff") == text + 63);
+
+        assert_se(find_line_startswith(emptystring, "") == emptystring);
+        assert_se(!find_line_startswith(emptystring, "x"));
+}
+
 DEFINE_TEST_MAIN(LOG_DEBUG);