Commit 309113c984c1f3157659dc1174e5d4218f610ae4
2011-11-29T23:45:17
Make initial value of git_buf ptr always be a valid empty string. Taking a page from core git's strbuf, this introduces git_buf_initbuf which is an empty string that is used to initialize the git_buf ptr value even for new buffers. Now the git_buf ptr will always point to a valid NUL-terminated string. This change required jumping through a few hoops for git_buf_grow and git_buf_free to distinguish between a actual allocated buffer and the global initial value. Also, this moves the allocation related functions to be next to each other near the top of buffer.c.
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diff --git a/src/buffer.c b/src/buffer.c
index aa66261..3dff813 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -8,13 +8,29 @@
#include "posix.h"
#include <stdarg.h>
+/* Used as default value for git_buf->ptr so that people can always
+ * assume ptr is non-NULL and zero terminated even for new git_bufs.
+ */
+char git_buf_initbuf[1];
+
#define ENSURE_SIZE(b, d) \
if ((ssize_t)(d) > buf->asize && git_buf_grow(b, (d)) < GIT_SUCCESS)\
return;
+void git_buf_init(git_buf *buf, size_t initial_size)
+{
+ buf->asize = 0;
+ buf->size = 0;
+ buf->ptr = git_buf_initbuf;
+
+ if (initial_size)
+ git_buf_grow(buf, initial_size);
+}
+
int git_buf_grow(git_buf *buf, size_t target_size)
{
char *new_ptr;
+ size_t new_size;
if (buf->asize < 0)
return GIT_ENOMEM;
@@ -22,27 +38,56 @@ int git_buf_grow(git_buf *buf, size_t target_size)
if (target_size <= (size_t)buf->asize)
return GIT_SUCCESS;
- if (buf->asize == 0)
- buf->asize = target_size;
+ if (buf->asize == 0) {
+ new_size = target_size;
+ new_ptr = NULL;
+ } else {
+ new_size = (size_t)buf->asize;
+ new_ptr = buf->ptr;
+ }
/* grow the buffer size by 1.5, until it's big enough
* to fit our target size */
- while (buf->asize < (int)target_size)
- buf->asize = (buf->asize << 1) - (buf->asize >> 1);
+ while (new_size < target_size)
+ new_size = (new_size << 1) - (new_size >> 1);
/* round allocation up to multiple of 8 */
- buf->asize = (buf->asize + 7) & ~7;
+ new_size = (new_size + 7) & ~7;
- new_ptr = git__realloc(buf->ptr, buf->asize);
+ new_ptr = git__realloc(new_ptr, new_size);
if (!new_ptr) {
buf->asize = -1;
return GIT_ENOMEM;
}
- buf->ptr = new_ptr;
+ buf->asize = new_size;
+ buf->ptr = new_ptr;
+
+ /* truncate the existing buffer size if necessary */
+ if (buf->size >= buf->asize)
+ buf->size = buf->asize - 1;
+ buf->ptr[buf->size] = '\0';
+
return GIT_SUCCESS;
}
+void git_buf_free(git_buf *buf)
+{
+ if (!buf) return;
+
+ if (buf->ptr != git_buf_initbuf)
+ git__free(buf->ptr);
+
+ git_buf_init(buf, 0);
+}
+
+void git_buf_clear(git_buf *buf)
+{
+ buf->size = 0;
+ if (buf->asize > 0)
+ buf->ptr[0] = '\0';
+}
+
int git_buf_oom(const git_buf *buf)
{
return (buf->asize < 0);
@@ -114,7 +159,7 @@ void git_buf_printf(git_buf *buf, const char *format, ...)
const char *git_buf_cstr(git_buf *buf)
{
- return buf->ptr ? buf->ptr : "";
+ return buf->ptr;
}
void git_buf_copy_cstr(char *data, size_t datasize, git_buf *buf)
@@ -135,23 +180,6 @@ void git_buf_copy_cstr(char *data, size_t datasize, git_buf *buf)
data[copylen] = '\0';
}
-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)
-{
- buf->size = 0;
- if (buf->ptr)
- *buf->ptr = '\0';
-}
-
void git_buf_consume(git_buf *buf, const char *end)
{
if (end > buf->ptr && end <= buf->ptr + buf->size) {
@@ -171,18 +199,12 @@ void git_buf_swap(git_buf *buf_a, git_buf *buf_b)
char *git_buf_take_cstr(git_buf *buf)
{
- char *data = NULL;
+ char *data = buf->ptr;
- if (buf->ptr == NULL)
+ if (buf->asize <= 0)
return NULL;
- assert(buf->asize > buf->size);
-
- data = buf->ptr;
-
- buf->ptr = NULL;
- buf->asize = 0;
- buf->size = 0;
+ git_buf_init(buf, 0);
return data;
}
diff --git a/src/buffer.h b/src/buffer.h
index 9e8ebd0..fa0c7f0 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -14,8 +14,11 @@ typedef struct {
ssize_t asize, size;
} git_buf;
-#define GIT_BUF_INIT {NULL, 0, 0}
+extern char git_buf_initbuf[];
+#define GIT_BUF_INIT { git_buf_initbuf, 0, 0 }
+
+void git_buf_init(git_buf *buf, size_t initial_size);
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);
diff --git a/tests-clay/core/buffer.c b/tests-clay/core/buffer.c
index 1abee3e..acde8c0 100644
--- a/tests-clay/core/buffer.c
+++ b/tests-clay/core/buffer.c
@@ -224,10 +224,7 @@ check_buf_append(
cl_assert(git_buf_oom(&tgt) == 0);
git_buf_puts(&tgt, data_b);
cl_assert(git_buf_oom(&tgt) == 0);
- if (expected_data == NULL)
- cl_assert(tgt.ptr == NULL);
- else
- cl_assert_strequal(expected_data, git_buf_cstr(&tgt));
+ cl_assert_strequal(expected_data, git_buf_cstr(&tgt));
cl_assert(tgt.size == expected_size);
if (expected_asize > 0)
cl_assert(tgt.asize == expected_asize);
@@ -356,13 +353,13 @@ void test_core_buffer__7(void)
b = git_buf_take_cstr(&a);
cl_assert_strequal("foo", b);
- cl_assert_strequal(NULL, a.ptr);
+ cl_assert_strequal("", a.ptr);
git__free(b);
b = git_buf_take_cstr(&a);
cl_assert_strequal(NULL, b);
- cl_assert_strequal(NULL, a.ptr);
+ cl_assert_strequal("", a.ptr);
git_buf_free(&a);
}