X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;ds=sidebyside;f=src%2Futils%2Fstrbuf.c;h=7d8bc5527f6138f7a1c8ad6cf6730c6445c3460b;hb=e747b18c932d05b21a2b3f03390a2997117dbcdb;hp=4d8fc8b91ba234df10edd8d15d552169bcbf9930;hpb=a6753b33e70f0934d4b34b19366eddda56f05d9c;p=sysdb.git

diff --git a/src/utils/strbuf.c b/src/utils/strbuf.c
index 4d8fc8b..7d8bc55 100644
--- a/src/utils/strbuf.c
+++ b/src/utils/strbuf.c
@@ -36,6 +36,14 @@
 
 #include <unistd.h>
 
+/* free memory if most of the buffer is unused */
+#define CHECK_SHRINK(strbuf) \
+	do { \
+		if ((strbuf)->pos < (strbuf)->size / 3) \
+			/* don't free all memory to avoid churn */ \
+			strbuf_resize((strbuf), 2 * (strbuf)->pos); \
+	} while (0)
+
 /*
  * private data structures
  */
@@ -55,14 +63,17 @@ strbuf_resize(sdb_strbuf_t *strbuf, size_t new_size)
 {
 	char *tmp;
 
-	if (new_size <= strbuf->size)
-		return 0;
+	if (new_size <= strbuf->pos)
+		return -1;
 
 	tmp = realloc(strbuf->string, new_size);
 	if (! tmp)
 		return -1;
 
-	strbuf->string = tmp;
+	if (new_size)
+		strbuf->string = tmp;
+	else
+		strbuf->string = NULL;
 	strbuf->size = new_size;
 	return 0;
 } /* strbuf_resize */
@@ -119,9 +130,14 @@ sdb_strbuf_vappend(sdb_strbuf_t *strbuf, const char *fmt, va_list ap)
 
 	assert((strbuf->size == 0) || (strbuf->string[strbuf->pos] == '\0'));
 
-	if (strbuf->pos >= strbuf->size)
+	if (! strbuf->size) {
 		/* use some arbitrary but somewhat reasonable default */
-		if (strbuf_resize(strbuf, strbuf->size ? 2 * strbuf->size : 64))
+		if (strbuf_resize(strbuf, 64))
+			return -1;
+	}
+	/* make sure to reserve space for the nul-byte */
+	else if (strbuf->pos >= strbuf->size - 1)
+		if (strbuf_resize(strbuf, 2 * strbuf->size))
 			return -1;
 
 	assert(strbuf->size && strbuf->string);
@@ -137,8 +153,12 @@ sdb_strbuf_vappend(sdb_strbuf_t *strbuf, const char *fmt, va_list ap)
 		return status;
 	}
 
+	/* 'status' does not include nul-byte */
 	if ((size_t)status >= strbuf->size - strbuf->pos) {
-		strbuf_resize(strbuf, (size_t)status + 1);
+		if (strbuf_resize(strbuf, strbuf->pos + (size_t)status + 1)) {
+			va_end(aq);
+			return -1;
+		}
 
 		/* reset string and try again */
 		strbuf->string[strbuf->pos] = '\0';
@@ -148,6 +168,11 @@ sdb_strbuf_vappend(sdb_strbuf_t *strbuf, const char *fmt, va_list ap)
 		strbuf->pos += (size_t)status;
 
 	va_end(aq);
+
+	/* even though this function always appends to the existing buffer, the
+	 * size might have previously been reset */
+	CHECK_SHRINK(strbuf);
+
 	return (ssize_t)status;
 } /* sdb_strbuf_vappend */
 
@@ -218,6 +243,10 @@ sdb_strbuf_memappend(sdb_strbuf_t *strbuf, const void *data, size_t n)
 	strbuf->pos += n;
 	strbuf->string[strbuf->pos] = '\0';
 
+	/* even though this function always appends to the existing buffer, the
+	 * size might have previously been reset */
+	CHECK_SHRINK(strbuf);
+
 	return (ssize_t)n;
 } /* sdb_strbuf_memappend */
 
@@ -243,8 +272,9 @@ sdb_strbuf_read(sdb_strbuf_t *strbuf, int fd, size_t n)
 	if (! strbuf)
 		return -1;
 
-	if (strbuf_resize(strbuf, strbuf->pos + n + 1))
-		return -1;
+	if (strbuf->pos + n + 1 >= strbuf->size)
+		if (strbuf_resize(strbuf, strbuf->pos + n + 1))
+			return -1;
 
 	ret = read(fd, strbuf->string + strbuf->pos, n);
 	if (ret > 0)
@@ -274,23 +304,48 @@ sdb_strbuf_chomp(sdb_strbuf_t *strbuf)
 } /* sdb_strbuf_chomp */
 
 void
-sdb_strbuf_skip(sdb_strbuf_t *strbuf, size_t n)
+sdb_strbuf_skip(sdb_strbuf_t *strbuf, size_t offset, size_t n)
 {
+	char *start;
+	size_t len;
+
 	if ((! strbuf) || (! n))
 		return;
 
-	if (n >= strbuf->pos) {
-		strbuf->string[0] = '\0';
-		strbuf->pos = 0;
+	if (offset >= strbuf->pos)
+		return;
+
+	len = strbuf->pos - offset;
+
+	if (n >= len) {
+		strbuf->string[offset] = '\0';
+		strbuf->pos = offset;
 		return;
 	}
 
-	assert(n < strbuf->pos);
-	memmove(strbuf->string, strbuf->string + n, strbuf->pos - n);
+	assert(offset + n < strbuf->pos);
+	assert(offset < strbuf->pos);
+
+	start = strbuf->string + offset;
+	memmove(start, start + n, len - n);
 	strbuf->pos -= n;
 	strbuf->string[strbuf->pos] = '\0';
+
+	/* don't resize now but wait for the next write to avoid churn */
 } /* sdb_strbuf_skip */
 
+void
+sdb_strbuf_clear(sdb_strbuf_t *strbuf)
+{
+	if ((! strbuf) || (! strbuf->size))
+		return;
+
+	strbuf->string[0] = '\0';
+	strbuf->pos = 0;
+
+	/* don't resize now but wait for the next write to avoid churn */
+} /* sdb_strbuf_clear */
+
 const char *
 sdb_strbuf_string(sdb_strbuf_t *strbuf)
 {
@@ -309,5 +364,13 @@ sdb_strbuf_len(sdb_strbuf_t *strbuf)
 	return strbuf->pos;
 } /* sdb_strbuf_string */
 
+size_t
+sdb_strbuf_cap(sdb_strbuf_t *strbuf)
+{
+	if (! strbuf)
+		return 0;
+	return strbuf->size;
+} /* sdb_strbuf_cap */
+
 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */