kernel: Add more sv functions and change interfaces

4 files changed, 33 insertions, 5 deletions

diff --git a/kernel/audio.c b/kernel/audio.c
index fe78938..0b1c4af 100644
--- a/kernel/audio.c
+++ b/kernel/audio.c
@@ -28,9 +28,10 @@ int volume_write(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
   (void)fd;
   struct sv string_view = sv_init(buffer, len);
   struct sv rest;
-  u64 volume = sv_parse_unsigned_number(string_view, &rest);
+  int got_num;
+  u64 volume = sv_parse_unsigned_number(string_view, &rest, &got_num);
   int i = sv_length(string_view) - sv_length(rest);
-  if (0 == i) {
+  if (!got_num) {
     return 0;
   }
 
diff --git a/kernel/lib/sv.c b/kernel/lib/sv.c
index 580e63a..2143a4b 100644
--- a/kernel/lib/sv.c
+++ b/kernel/lib/sv.c
@@ -54,7 +54,11 @@ struct sv sv_skip_chars(const struct sv input, const char *chars) {
   return r;
 }
 
-uint64_t sv_parse_unsigned_number(struct sv input, struct sv *rest) {
+uint64_t sv_parse_unsigned_number(struct sv input, struct sv *rest,
+                                  int *got_num) {
+  if (got_num) {
+    *got_num = 0;
+  }
   uint64_t r = 0;
   size_t i = 0;
   for (; i < input.length; i++) {
@@ -64,6 +68,11 @@ uint64_t sv_parse_unsigned_number(struct sv input, struct sv *rest) {
     r *= 10;
     r += input.s[i] - '0';
   }
+  if (i > 0) {
+    if (got_num) {
+      *got_num = 1;
+    }
+  }
   input.length -= i;
   input.s += i;
   if (rest) {
@@ -229,6 +238,23 @@ struct sv sv_clone(struct sv s) {
   return new_sv;
 }
 
+int sv_try_eat(struct sv input, struct sv *rest, struct sv b) {
+  if (input.length < b.length) {
+    return 0;
+  }
+  for (size_t i = 0; i < b.length; i++) {
+    if (input.s[i] != b.s[i]) {
+      return 0;
+    }
+  }
+  input.s += b.length;
+  input.length -= b.length;
+  if (rest) {
+    *rest = input;
+  }
+  return 1;
+}
+
 char *sv_copy_to_c(struct sv s, char *out, size_t buffer_length) {
   int copy_len = min(s.length + 1, buffer_length);
   if (0 == copy_len) {
diff --git a/kernel/lib/sv.h b/kernel/lib/sv.h
index b5cb0c9..bd556d4 100644
--- a/kernel/lib/sv.h
+++ b/kernel/lib/sv.h
@@ -28,6 +28,7 @@ struct sv sv_split_space(const struct sv input, struct sv *rest);
 struct sv sv_skip_chars(const struct sv input, const char *chars);
 struct sv sv_split_function(const struct sv input, struct sv *rest,
                             int (*function)(int));
+int sv_try_eat(struct sv input, struct sv *rest, struct sv b);
 struct sv sv_take(struct sv s, struct sv *rest, size_t n);
 struct sv sv_take_end(struct sv s, struct sv *rest, size_t n);
 struct sv sv_next(struct sv s);
@@ -39,5 +40,5 @@ struct sv sv_trim_left(struct sv s, size_t n);
 struct sv sv_clone(struct sv s);
 struct sv sv_clone_from_c(const char *s);
 char *sv_copy_to_c(struct sv s, char *out, size_t buffer_length);
-uint64_t sv_parse_unsigned_number(struct sv input, struct sv *rest);
+uint64_t sv_parse_unsigned_number(struct sv input, struct sv *rest, int *got_num);
 #endif
diff --git a/kernel/timer.c b/kernel/timer.c
index b84c16a..6321cda 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -61,7 +61,7 @@ int clock_write(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
 
   struct sv string_view = sv_init(buffer, len);
 
-  u64 new_value_ms = sv_parse_unsigned_number(string_view, &string_view);
+  u64 new_value_ms = sv_parse_unsigned_number(string_view, &string_view, NULL);
 
   i64 new_value_seconds = new_value_ms / 1000;