[libvirt] [PATCH 20/20] Use virBufferPtr for sexpr2string instead of manual buffer handling
Matthias Bolte
matthias.bolte at googlemail.com
Sun Apr 3 09:21:33 UTC 2011
Removes 4kb stack allocation in the XenD subdriver.
---
src/util/sexpr.c | 142 +++++++++++++++++++++++------------------------
src/util/sexpr.h | 3 +-
src/xen/xend_internal.c | 17 +++++-
3 files changed, 86 insertions(+), 76 deletions(-)
diff --git a/src/util/sexpr.c b/src/util/sexpr.c
index 7f14206..ae1692a 100644
--- a/src/util/sexpr.c
+++ b/src/util/sexpr.c
@@ -199,78 +199,56 @@ sexpr_append(struct sexpr *lst, const struct sexpr *value)
* sexpr2string:
* @sexpr: an S-Expression pointer
* @buffer: the output buffer
- * @n_buffer: the size of the buffer in bytes
*
* Serialize the S-Expression in the buffer.
- * Note that the output may be truncated if @n_buffer is too small
- * resulting in an unparseable value.
*
- * Returns the number of bytes used by the serialization in the buffer or
- * 0 in case of error.
+ * Returns 0 on success, -1 on error.
*/
-size_t
-sexpr2string(const struct sexpr * sexpr, char *buffer, size_t n_buffer)
+int
+sexpr2string(const struct sexpr *sexpr, virBufferPtr buffer)
{
- size_t ret = 0, tmp;
-
- if ((sexpr == NULL) || (buffer == NULL) || (n_buffer <= 0))
- return (0);
+ if ((sexpr == NULL) || (buffer == NULL))
+ return -1;
switch (sexpr->kind) {
- case SEXPR_CONS:
- tmp = snprintf(buffer + ret, n_buffer - ret, "(");
- if (tmp == 0)
- goto error;
- ret += tmp;
- tmp = sexpr2string(sexpr->u.s.car, buffer + ret, n_buffer - ret);
- if (tmp == 0)
- goto error;
- ret += tmp;
- while (sexpr->u.s.cdr->kind != SEXPR_NIL) {
- sexpr = sexpr->u.s.cdr;
- tmp = snprintf(buffer + ret, n_buffer - ret, " ");
- if (tmp == 0)
- goto error;
- ret += tmp;
- tmp =
- sexpr2string(sexpr->u.s.car, buffer + ret, n_buffer - ret);
- if (tmp == 0)
- goto error;
- ret += tmp;
- }
- tmp = snprintf(buffer + ret, n_buffer - ret, ")");
- if (tmp == 0)
- goto error;
- ret += tmp;
- break;
- case SEXPR_VALUE:
- if (strchr(sexpr->u.value, ' ') ||
- strchr(sexpr->u.value, ')') ||
- strchr(sexpr->u.value, '('))
- tmp = snprintf(buffer + ret, n_buffer - ret, "'%s'",
- sexpr->u.value);
- else
- tmp = snprintf(buffer + ret, n_buffer - ret, "%s",
- sexpr->u.value);
- if (tmp == 0)
- goto error;
- ret += tmp;
- break;
- case SEXPR_NIL:
- tmp = snprintf(buffer + ret, n_buffer - ret, "()");
- if (tmp == 0)
- goto error;
- ret += tmp;
- break;
- default:
+ case SEXPR_CONS:
+ virBufferAddChar(buffer, '(');
+
+ if (sexpr2string(sexpr->u.s.car, buffer) < 0)
goto error;
+
+ while (sexpr->u.s.cdr->kind != SEXPR_NIL) {
+ sexpr = sexpr->u.s.cdr;
+
+ virBufferAddChar(buffer, ' ');
+
+ if (sexpr2string(sexpr->u.s.car, buffer) < 0)
+ goto error;
+ }
+
+ virBufferAddChar(buffer, ')');
+ break;
+ case SEXPR_VALUE:
+ if (strchr(sexpr->u.value, ' ') ||
+ strchr(sexpr->u.value, ')') ||
+ strchr(sexpr->u.value, '('))
+ virBufferVSprintf(buffer, "'%s'", sexpr->u.value);
+ else
+ virBufferVSprintf(buffer, "%s", sexpr->u.value);
+
+ break;
+ case SEXPR_NIL:
+ virBufferAddLit(buffer, "()");
+ break;
+ default:
+ goto error;
}
- return (ret);
+ return 0;
+
error:
- buffer[n_buffer - 1] = 0;
- virSexprError(VIR_ERR_SEXPR_SERIAL, "%s", buffer);
- return (0);
+ virSexprError(VIR_ERR_SEXPR_SERIAL, NULL);
+ return -1;
}
#define IS_SPACE(c) ((c == 0x20) || (c == 0x9) || (c == 0xD) || (c == 0xA))
@@ -413,22 +391,28 @@ string2sexpr(const char *buffer)
static struct sexpr *
sexpr_lookup_key(const struct sexpr *sexpr, const char *node)
{
- char buffer[4096], *ptr, *token;
+ struct sexpr *result = NULL;
+ char *buffer, *ptr, *token;
if ((node == NULL) || (sexpr == NULL))
- return (NULL);
+ return NULL;
- snprintf(buffer, sizeof(buffer), "%s", node);
+ buffer = strdup(node);
+
+ if (buffer == NULL) {
+ virReportOOMError();
+ return NULL;
+ }
ptr = buffer;
token = strsep(&ptr, "/");
if (sexpr->kind != SEXPR_CONS || sexpr->u.s.car->kind != SEXPR_VALUE) {
- return NULL;
+ goto cleanup;
}
if (STRNEQ(sexpr->u.s.car->u.value, token)) {
- return NULL;
+ goto cleanup;
}
for (token = strsep(&ptr, "/"); token; token = strsep(&ptr, "/")) {
@@ -454,10 +438,15 @@ sexpr_lookup_key(const struct sexpr *sexpr, const char *node)
}
if (token != NULL) {
- return NULL;
+ goto cleanup;
}
- return (struct sexpr *) sexpr;
+ result = (struct sexpr *) sexpr;
+
+cleanup:
+ VIR_FREE(buffer);
+
+ return result;
}
/**
@@ -550,21 +539,30 @@ int sexpr_node_copy(const struct sexpr *sexpr, const char *node, char **dst)
* @... extra data to build the path
*
* Search a node value in the S-Expression based on its path
- * NOTE: path are limited to 4096 bytes.
*
* Returns the value of the node or NULL if not found.
*/
const char *
sexpr_fmt_node(const struct sexpr *sexpr, const char *fmt, ...)
{
+ int result;
va_list ap;
- char node[4096];
+ char *node;
+ const char *value;
va_start(ap, fmt);
- vsnprintf(node, sizeof(node), fmt, ap);
+ result = virVasprintf(&node, fmt, ap);
va_end(ap);
- return sexpr_node(sexpr, node);
+ if (result < 0) {
+ return NULL;
+ }
+
+ value = sexpr_node(sexpr, node);
+
+ VIR_FREE(node);
+
+ return value;
}
/**
diff --git a/src/util/sexpr.h b/src/util/sexpr.h
index dc6687d..8dfd89a 100644
--- a/src/util/sexpr.h
+++ b/src/util/sexpr.h
@@ -14,6 +14,7 @@
# define _LIBVIR_SEXPR_H_
# include "internal.h"
+# include "buf.h"
# include <sys/types.h>
# include <stdint.h>
@@ -36,7 +37,7 @@ struct sexpr {
};
/* conversion to/from strings */
-size_t sexpr2string(const struct sexpr *sexpr, char *buffer, size_t n_buffer);
+int sexpr2string(const struct sexpr *sexpr, virBufferPtr buffer);
struct sexpr *string2sexpr(const char *buffer);
/* constructors and destructors */
diff --git a/src/xen/xend_internal.c b/src/xen/xend_internal.c
index 8b07a8a..04122ba 100644
--- a/src/xen/xend_internal.c
+++ b/src/xen/xend_internal.c
@@ -3023,7 +3023,8 @@ xenDaemonDomainSetAutostart(virDomainPtr domain,
int autostart)
{
struct sexpr *root, *autonode;
- char buf[4096];
+ virBuffer buffer = VIR_BUFFER_INITIALIZER;
+ char *content = NULL;
int ret = -1;
xenUnifiedPrivatePtr priv;
@@ -3065,12 +3066,20 @@ xenDaemonDomainSetAutostart(virDomainPtr domain,
goto error;
}
- if (sexpr2string(root, buf, sizeof(buf)) == 0) {
+ if (sexpr2string(root, &buffer) < 0) {
virXendError(VIR_ERR_INTERNAL_ERROR,
"%s", _("sexpr2string failed"));
goto error;
}
- if (xend_op(domain->conn, "", "op", "new", "config", buf, NULL) != 0) {
+
+ if (virBufferError(&buffer)) {
+ virReportOOMError();
+ goto error;
+ }
+
+ content = virBufferContentAndReset(&buffer);
+
+ if (xend_op(domain->conn, "", "op", "new", "config", content, NULL) != 0) {
virXendError(VIR_ERR_XEN_CALL,
"%s", _("Failed to redefine sexpr"));
goto error;
@@ -3083,6 +3092,8 @@ xenDaemonDomainSetAutostart(virDomainPtr domain,
ret = 0;
error:
+ virBufferFreeAndReset(&buffer);
+ VIR_FREE(content);
sexpr_free(root);
return ret;
}
--
1.7.0.4
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