Merge pull request #499 from arrbee/extend-git-buf

Extend git_buf with new utility functions and unit tests.

src/buffer.c

@@ -9,7 +9,7 @@
 #include <stdarg.h>
 
 #define ENSURE_SIZE(b, d) \
-	if ((ssize_t)(d) >= buf->asize && git_buf_grow(b, (d)) < GIT_SUCCESS)\
+	if ((ssize_t)(d) > buf->asize && git_buf_grow(b, (d)) < GIT_SUCCESS)\
 		return;
 
 int git_buf_grow(git_buf *buf, size_t target_size)
@@ -19,6 +19,9 @@ int git_buf_grow(git_buf *buf, size_t target_size)
 	if (buf->asize < 0)
 		return GIT_ENOMEM;
 
+	if (target_size <= (size_t)buf->asize)
+		return GIT_SUCCESS;
+
 	if (buf->asize == 0)
 		buf->asize = target_size;
 
@@ -27,6 +30,9 @@ int git_buf_grow(git_buf *buf, size_t target_size)
 	while (buf->asize < (int)target_size)
 		buf->asize = (buf->asize << 1) - (buf->asize >> 1);
 
+	/* round allocation up to multiple of 8 */
+	buf->asize = (buf->asize + 7) & ~7;
+
 	new_ptr = git__realloc(buf->ptr, buf->asize);
 	if (!new_ptr) {
 		buf->asize = -1;
@@ -42,6 +48,22 @@ int git_buf_oom(const git_buf *buf)
 	return (buf->asize < 0);
 }
 
+void git_buf_set(git_buf *buf, const char *data, size_t len)
+{
+	if (len == 0 || data == NULL) {
+		git_buf_clear(buf);
+	} else {
+		ENSURE_SIZE(buf, len);
+		memmove(buf->ptr, data, len);
+		buf->size = len;
+	}
+}
+
+void git_buf_sets(git_buf *buf, const char *string)
+{
+	git_buf_set(buf, string, string ? strlen(string) : 0);
+}
+
 void git_buf_putc(git_buf *buf, char c)
 {
 	ENSURE_SIZE(buf, buf->size + 1);
@@ -51,12 +73,13 @@ void git_buf_putc(git_buf *buf, char c)
 void git_buf_put(git_buf *buf, const char *data, size_t len)
 {
 	ENSURE_SIZE(buf, buf->size + len);
-	memcpy(buf->ptr + buf->size, data, len);
+	memmove(buf->ptr + buf->size, data, len);
 	buf->size += len;
 }
 
 void git_buf_puts(git_buf *buf, const char *string)
 {
+	assert(string);
 	git_buf_put(buf, string, strlen(string));
 }
 
@@ -88,7 +111,8 @@ void git_buf_printf(git_buf *buf, const char *format, ...)
 
 const char *git_buf_cstr(git_buf *buf)
 {
-	if (buf->size + 1 >= buf->asize && git_buf_grow(buf, buf->size + 1) < GIT_SUCCESS)
+	if (buf->size + 1 > buf->asize &&
+		git_buf_grow(buf, buf->size + 1) < GIT_SUCCESS)
 		return NULL;
 
 	buf->ptr[buf->size] = '\0';
@@ -97,7 +121,12 @@ const char *git_buf_cstr(git_buf *buf)
 
 void git_buf_free(git_buf *buf)
 {
+	if (!buf) return;
+
 	git__free(buf->ptr);
+	buf->ptr = NULL;
+	buf->asize = 0;
+	buf->size = 0;
 }
 
 void git_buf_clear(git_buf *buf)
@@ -107,7 +136,164 @@ void git_buf_clear(git_buf *buf)
 
 void git_buf_consume(git_buf *buf, const char *end)
 {
-	size_t consumed = end - buf->ptr;
-	memmove(buf->ptr, end, buf->size - consumed);
-	buf->size -= consumed;
+	if (end > buf->ptr && end <= buf->ptr + buf->size) {
+		size_t consumed = end - buf->ptr;
+		memmove(buf->ptr, end, buf->size - consumed);
+		buf->size -= consumed;
+	}
+}
+
+void git_buf_swap(git_buf *buf_a, git_buf *buf_b)
+{
+	git_buf t = *buf_a;
+	*buf_a = *buf_b;
+	*buf_b = t;
+}
+
+char *git_buf_take_cstr(git_buf *buf)
+{
+	char *data = NULL;
+
+	if (buf->ptr == NULL)
+		return NULL;
+
+	if (buf->size + 1 > buf->asize &&
+		git_buf_grow(buf, buf->size + 1) < GIT_SUCCESS)
+		return NULL;
+
+	data = buf->ptr;
+	data[buf->size] = '\0';
+
+	buf->ptr = NULL;
+	buf->asize = 0;
+	buf->size = 0;
+
+	return data;
+}
+
+void git_buf_join_n(git_buf *buf, char separator, int nbuf, ...)
+{
+	/* Make two passes to avoid multiple reallocation */
+
+	va_list ap;
+	int i;
+	size_t total_size = 0;
+	char *out;
+
+	if (buf->size > 0 && buf->ptr[buf->size - 1] != separator)
+		++total_size; /* space for initial separator */
+
+	va_start(ap, nbuf);
+	for (i = 0; i < nbuf; ++i) {
+		const char* segment;
+		size_t segment_len;
+
+		segment = va_arg(ap, const char *);
+		if (!segment)
+			continue;
+
+		segment_len = strlen(segment);
+		total_size += segment_len;
+		if (segment_len == 0 || segment[segment_len - 1] != separator)
+			++total_size; /* space for separator */
+	}
+	va_end(ap);
+
+	ENSURE_SIZE(buf, buf->size + total_size);
+
+	out = buf->ptr + buf->size;
+
+	/* append separator to existing buf if needed */
+	if (buf->size > 0 && out[-1] != separator)
+		*out++ = separator;
+
+	va_start(ap, nbuf);
+	for (i = 0; i < nbuf; ++i) {
+		const char* segment;
+		size_t segment_len;
+
+		segment = va_arg(ap, const char *);
+		if (!segment)
+			continue;
+
+		/* skip leading separators */
+		if (out > buf->ptr && out[-1] == separator)
+			while (*segment == separator) segment++;
+
+		/* copy over next buffer */
+		segment_len = strlen(segment);
+		if (segment_len > 0) {
+			memmove(out, segment, segment_len);
+			out += segment_len;
+		}
+
+		/* append trailing separator (except for last item) */
+		if (i < nbuf - 1 && out > buf->ptr && out[-1] != separator)
+			*out++ = separator;
+	}
+	va_end(ap);
+
+	/* set size based on num characters actually written */
+	buf->size = out - buf->ptr;
+}
+
+void git_buf_join(
+	git_buf *buf,
+	char separator,
+	const char *str_a,
+	const char *str_b)
+{
+	size_t add_size = 0;
+	size_t sep_a = 0;
+	size_t strlen_a = 0;
+	size_t sep_b = 0;
+	size_t strlen_b = 0;
+	char *ptr;
+
+	/* calculate string lengths and need for added separators */
+	if (str_a) {
+		while (*str_a == separator) { sep_a = 1; str_a++; }
+		strlen_a = strlen(str_a);
+	}
+	if (str_b) {
+		while (*str_b == separator) { sep_b = 1; str_b++; }
+		strlen_b = strlen(str_b);
+	}
+	if (buf->size > 0) {
+		if (buf->ptr[buf->size - 1] == separator) {
+			sep_a = 0;
+			if (!strlen_a) sep_b = 0;
+		} else if (!strlen_a)
+			sep_b = (str_b != NULL);
+	}
+	if (strlen_a > 0) {
+		if (str_a[strlen_a - 1] == separator)
+			sep_b = 0;
+		else if (str_b)
+			sep_b = 1;
+	}
+
+	add_size = sep_a + strlen_a + sep_b + strlen_b;
+
+	if (!add_size) return;
+
+	ENSURE_SIZE(buf, buf->size + add_size);
+
+	/* concatenate strings */
+	ptr = buf->ptr + buf->size;
+	if (sep_a)
+		*ptr++ = separator;
+	if (strlen_a) {
+		memmove(ptr, str_a, strlen_a);
+		ptr += strlen_a;
+	}
+	if (sep_b)
+		*ptr++ = separator;
+	if (strlen_b) {
+		memmove(ptr, str_b, strlen_b);
+		ptr += strlen_b;
+	}
+
+	/* set size based on num characters actually written */
+	buf->size = ptr - buf->ptr;
 }

src/buffer.h

@@ -17,15 +17,31 @@ typedef struct {
 #define GIT_BUF_INIT {NULL, 0, 0}
 
 int git_buf_grow(git_buf *buf, size_t target_size);
+void git_buf_free(git_buf *buf);
+void git_buf_swap(git_buf *buf_a, git_buf *buf_b);
+
+/**
+ * Any function that writes to a git_buf can fail due to memory allocation
+ * issues.  If one fails, the git_buf will be marked with an OOM error and
+ * further calls to modify the buffer will fail.  You just check
+ * git_buf_oom() at the end of your sequence and it will be true if you ran
+ * out of memory at any point with that buffer.
+ */
 int git_buf_oom(const git_buf *buf);
+
+void git_buf_set(git_buf *buf, const char *data, size_t len);
+void git_buf_sets(git_buf *buf, const char *string);
 void git_buf_putc(git_buf *buf, char c);
 void git_buf_put(git_buf *buf, const char *data, size_t len);
 void git_buf_puts(git_buf *buf, const char *string);
 void git_buf_printf(git_buf *buf, const char *format, ...) GIT_FORMAT_PRINTF(2, 3);
-const char *git_buf_cstr(git_buf *buf);
-void git_buf_free(git_buf *buf);
 void git_buf_clear(git_buf *buf);
 void git_buf_consume(git_buf *buf, const char *end);
+void git_buf_join_n(git_buf *buf, char separator, int nbuf, ...);
+void git_buf_join(git_buf *buf, char separator, const char *str_a, const char *str_b);
+
+const char *git_buf_cstr(git_buf *buf);
+char *git_buf_take_cstr(git_buf *buf);
 
 #define git_buf_PUTS(buf, str) git_buf_put(buf, str, sizeof(str) - 1)
 

tests-clay/clay_libgit2.h

@@ -25,4 +25,20 @@
  */
 #define cl_git_fail(expr) cl_must_fail(expr)
 
+/**
+ * Wrapper for string comparison that knows about nulls.
+ */
+#define cl_assert_strequal(a,b) \
+	cl_assert_strequal_internal(a,b,__FILE__,__LINE__)
+
+GIT_INLINE(void) cl_assert_strequal_internal(const char *a, const char *b, const char *file, int line)
+{
+	int match = (a == NULL || b == NULL) ? (a == b) : (strcmp(a, b) == 0);
+	if (!match) {
+		char buf[4096];
+		snprintf(buf, 4096, "'%s' != '%s'", a, b);
+		clay__assert(0, file, line, buf, "Strings do not match", 1);
+	}
+}
+
 #endif