Various useful helpers (#41684)

Split out of #41543.

These don't make too much sense on their own, but they also don't really
hurt. They are preparation for #41543, but in order to make things
either to review I split these four commits out, since they are not
directly part of what the PR shall achieve

src/basic/parse-util.h

@@ -83,6 +83,11 @@ static inline int safe_atou64(const char *s, uint64_t *ret_u) {
         return safe_atollu(s, (unsigned long long*) ret_u);
 }
 
+static inline int safe_atou64_full(const char *s, unsigned base, uint64_t *ret_u) {
+        assert_cc(sizeof(uint64_t) == sizeof(unsigned long long));
+        return safe_atollu_full(s, base, (unsigned long long*) ret_u);
+}
+
 static inline int safe_atoi64(const char *s, int64_t *ret_i) {
         assert_cc(sizeof(int64_t) == sizeof(long long));
         return safe_atolli(s, (long long*) ret_i);

src/basic/stat-util.c

@@ -898,3 +898,20 @@ mode_t inode_type_from_string(const char *s) {
 
         return MODE_INVALID;
 }
+
+int vfs_free_bytes(int fd, uint64_t *ret) {
+        assert(fd >= 0);
+        assert(ret);
+
+        /* Safely returns the current available disk space (for root, i.e. including any space reserved for
+         * root) of the disk referenced by the fd, converted to bytes. */
+
+        struct statvfs sv;
+        if (fstatvfs(fd, &sv) < 0)
+                return -errno;
+
+        if (!MUL_SAFE(ret, (uint64_t) sv.f_frsize, (uint64_t) sv.f_bfree))
+                return -ERANGE;
+
+        return 0;
+}

src/basic/stat-util.h

@@ -161,3 +161,5 @@ static inline bool inode_type_can_hardlink(mode_t m) {
          * type). */
         return IN_SET(m & S_IFMT, S_IFSOCK, S_IFLNK, S_IFREG, S_IFBLK, S_IFCHR, S_IFIFO);
 }
+
+int vfs_free_bytes(int fd, uint64_t *ret);

src/basic/string-util.c

@@ -1519,17 +1519,32 @@ char* strrstr_internal(const char *haystack, const char *needle) {
 
         /* Special case: for the empty string we return the very last possible occurrence, i.e. *after* the
          * last char, not before. */
-        if (*needle == 0)
+        if (needle[0] == 0)
                 return (char*) strchr(haystack, 0);
 
+        /* Special case: for single character strings, just use optimized strrchr() */
+        if (needle[1] == 0)
+                return (char*) strrchr(haystack, needle[0]);
+
         for (const char *p = strstr(haystack, needle), *q; p; p = q) {
                 q = strstr(p + 1, needle);
                 if (!q)
-                        return (char *) p;
+                        return (char*) p;
         }
         return NULL;
 }
 
+char* strrstr_no_case_internal(const char *haystack, const char *needle) {
+        if (!haystack || !needle)
+                return NULL;
+
+        for (const char *p = strchr(haystack, 0); p > haystack; p--)
+                if (startswith_no_case(p, needle))
+                        return (char*) p;
+
+        return startswith_no_case(haystack, needle) ? (char*) haystack : NULL;
+}
+
 size_t str_common_prefix(const char *a, const char *b) {
         assert(a);
         assert(b);

src/basic/string-util.h

@@ -312,4 +312,8 @@ char* strrstr_internal(const char *haystack, const char *needle) _pure_;
 #define strrstr(haystack, needle) \
         const_generic(haystack, strrstr_internal(haystack, needle))
 
+char* strrstr_no_case_internal(const char *haystack, const char *needle) _pure_;
+#define strrstr_no_case(haystack, needle) \
+        const_generic(haystack, strrstr_no_case_internal(haystack, needle))
+
 size_t str_common_prefix(const char *a, const char *b) _pure_;