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Eliminated various large (8KB) string buffers from the stack in

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mod_include by adding support for a power-of-two pool-based allocator
in ap_ssi_parse_string(). (The default operation of this function
is backward-compatible, to support the other modules that call it.)
This change should help reduce memory usage for servers delivering
shtml pages.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@92747 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Brian Pane
2002-01-06 06:41:30 +00:00
parent 1a24d5bb5c
commit c4e9b1f0a1
2 changed files with 103 additions and 33 deletions
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132
modules/filters/mod_include.c
View File

@@ -899,28 +899,63 @@ static void ap_ssi_get_tag_and_value(include_ctx_t *ctx, char **tag,
return;
}
/* initial buffer size for power-of-two allocator in ap_ssi_parse_string */
#define PARSE_STRING_INITIAL_SIZE 64
/*
* Do variable substitution on strings
* (Note: If out==NULL, this function allocs a buffer for the resulting
* string from r->pool. The return value is the parsed string)
*/
static void ap_ssi_parse_string(request_rec *r, include_ctx_t *ctx,
const char *in, char *out,
size_t length, int leave_name)
static char *ap_ssi_parse_string(request_rec *r, include_ctx_t *ctx,
const char *in, char *out,
apr_size_t length, int leave_name)
{
char ch;
char *next = out;
char *next;
char *end_out;
apr_size_t out_size;
/* allocate an output buffer if needed */
if (!out) {
out_size = PARSE_STRING_INITIAL_SIZE;
if (out_size > length) {
out_size = length;
}
out = apr_palloc(r->pool, out_size);
}
else {
out_size = length;
}
/* leave room for nul terminator */
end_out = out + length - 1;
end_out = out + out_size - 1;
next = out;
while ((ch = *in++) != '\0') {
switch (ch) {
case '\\':
if (next == end_out) {
/* truncated */
*next = '\0';
return;
if (out_size < length) {
/* double the buffer size */
apr_size_t new_out_size = out_size * 2;
apr_size_t current_length = next - out;
char *new_out;
if (new_out_size > length) {
new_out_size = length;
}
new_out = apr_palloc(r->pool, new_out_size);
memcpy(new_out, out, current_length);
out = new_out;
out_size = new_out_size;
end_out = out + out_size - 1;
next = out + current_length;
}
else {
/* truncated */
*next = '\0';
return out;
}
}
if (*in == '$') {
*next++ = *in++;
@@ -948,7 +983,7 @@ static void ap_ssi_parse_string(request_rec *r, include_ctx_t *ctx,
0, r, "Missing '}' on variable \"%s\"",
expansion);
*next = '\0';
return;
return out;
}
temp_end = in;
end_of_var_name = (char *)temp_end;
@@ -988,6 +1023,24 @@ static void ap_ssi_parse_string(request_rec *r, include_ctx_t *ctx,
* copied */
l = 1;
}
if ((next + l > end_out) && (out_size < length)) {
/* increase the buffer size to accommodate l more chars */
apr_size_t new_out_size = out_size;
apr_size_t current_length = next - out;
char *new_out;
do {
new_out_size *= 2;
} while (new_out_size < current_length + l);
if (new_out_size > length) {
new_out_size = length;
}
new_out = apr_palloc(r->pool, new_out_size);
memcpy(new_out, out, current_length);
out = new_out;
out_size = new_out_size;
end_out = out + out_size - 1;
next = out + current_length;
}
l = ((int)l > end_out - next) ? (end_out - next) : l;
memcpy(next, expansion, l);
next += l;
@@ -995,16 +1048,33 @@ static void ap_ssi_parse_string(request_rec *r, include_ctx_t *ctx,
}
default:
if (next == end_out) {
/* truncated */
*next = '\0';
return;
if (out_size < length) {
/* double the buffer size */
apr_size_t new_out_size = out_size * 2;
apr_size_t current_length = next - out;
char *new_out;
if (new_out_size > length) {
new_out_size = length;
}
new_out = apr_palloc(r->pool, new_out_size);
memcpy(new_out, out, current_length);
out = new_out;
out_size = new_out_size;
end_out = out + out_size - 1;
next = out + current_length;
}
else {
/* truncated */
*next = '\0';
return out;
}
}
*next++ = ch;
break;
}
}
*next = '\0';
return;
return out;
}
/* --------------------------- Action handlers ---------------------------- */
@@ -1056,7 +1126,7 @@ static int handle_include(include_ctx_t *ctx, apr_bucket_brigade **bb,
char *tag = NULL;
char *tag_val = NULL;
apr_bucket *tmp_buck;
char parsed_string[MAX_STRING_LEN];
char *parsed_string;
int loglevel = APLOG_ERR;
*inserted_head = NULL;
@@ -1075,8 +1145,8 @@ static int handle_include(include_ctx_t *ctx, apr_bucket_brigade **bb,
request_rec *rr = NULL;
char *error_fmt = NULL;
ap_ssi_parse_string(r, ctx, tag_val, parsed_string,
sizeof(parsed_string), 0);
parsed_string = ap_ssi_parse_string(r, ctx, tag_val, NULL,
MAX_STRING_LEN, 0);
if (tag[0] == 'f') {
/* XXX: Port to apr_filepath_merge
* be safe; only files in this directory or below allowed
@@ -1283,7 +1353,7 @@ static int handle_config(include_ctx_t *ctx, apr_bucket_brigade **bb,
{
char *tag = NULL;
char *tag_val = NULL;
char parsed_string[MAX_STRING_LEN];
char *parsed_string;
apr_table_t *env = r->subprocess_env;
*inserted_head = NULL;
@@ -1325,8 +1395,8 @@ static int handle_config(include_ctx_t *ctx, apr_bucket_brigade **bb,
ctx->time_str, 0));
}
else if (!strcmp(tag, "sizefmt")) {
ap_ssi_parse_string(r, ctx, tag_val, parsed_string,
sizeof(parsed_string), 0);
parsed_string = ap_ssi_parse_string(r, ctx, tag_val, NULL,
MAX_STRING_LEN, 0);
decodehtml(parsed_string);
if (!strcmp(parsed_string, "bytes")) {
ctx->flags |= FLAG_SIZE_IN_BYTES;
@@ -1435,7 +1505,7 @@ static int handle_fsize(include_ctx_t *ctx, apr_bucket_brigade **bb,
apr_finfo_t finfo;
apr_size_t s_len;
apr_bucket *tmp_buck;
char parsed_string[MAX_STRING_LEN];
char *parsed_string;
*inserted_head = NULL;
if (ctx->flags & FLAG_PRINTING) {
@@ -1450,8 +1520,8 @@ static int handle_fsize(include_ctx_t *ctx, apr_bucket_brigade **bb,
}
}
else {
ap_ssi_parse_string(r, ctx, tag_val, parsed_string,
sizeof(parsed_string), 0);
parsed_string = ap_ssi_parse_string(r, ctx, tag_val, NULL,
MAX_STRING_LEN, 0);
if (!find_file(r, "fsize", tag, parsed_string, &finfo)) {
/* XXX: if we *know* we're going to have to copy the
* thing off of the stack anyway, why not palloc buff
@@ -1506,7 +1576,7 @@ static int handle_flastmod(include_ctx_t *ctx, apr_bucket_brigade **bb,
apr_finfo_t finfo;
apr_size_t t_len;
apr_bucket *tmp_buck;
char parsed_string[MAX_STRING_LEN];
char *parsed_string;
*inserted_head = NULL;
if (ctx->flags & FLAG_PRINTING) {
@@ -1521,8 +1591,8 @@ static int handle_flastmod(include_ctx_t *ctx, apr_bucket_brigade **bb,
}
}
else {
ap_ssi_parse_string(r, ctx, tag_val, parsed_string,
sizeof(parsed_string), 0);
parsed_string = ap_ssi_parse_string(r, ctx, tag_val, NULL,
MAX_STRING_LEN, 0);
if (!find_file(r, "flastmod", tag, parsed_string, &finfo)) {
char *t_val;
@@ -1760,7 +1830,7 @@ static int parse_expr(request_rec *r, include_ctx_t *ctx, const char *expr,
int value, done;
} *root, *current, *new;
const char *parse;
char buffer[MAX_STRING_LEN];
char* buffer;
apr_pool_t *expr_pool;
int retval = 0;
apr_size_t debug_pos = 0;
@@ -2109,8 +2179,8 @@ static int parse_expr(request_rec *r, include_ctx_t *ctx, const char *expr,
sizeof (" Evaluate string\n"));
debug_pos += sizeof (" Evaluate string\n");
#endif
ap_ssi_parse_string(r, ctx, current->token.value, buffer,
sizeof(buffer), 0);
buffer = ap_ssi_parse_string(r, ctx, current->token.value, NULL,
MAX_STRING_LEN, 0);
apr_cpystrn(current->token.value, buffer,
sizeof(current->token.value));
current->value = (current->token.value[0] != '\0');
@@ -2648,7 +2718,7 @@ static int handle_set(include_ctx_t *ctx, apr_bucket_brigade **bb,
char *tag_val = NULL;
char *var = NULL;
apr_bucket *tmp_buck;
char parsed_string[MAX_STRING_LEN];
char *parsed_string;
*inserted_head = NULL;
if (ctx->flags & FLAG_PRINTING) {
@@ -2672,8 +2742,8 @@ static int handle_set(include_ctx_t *ctx, apr_bucket_brigade **bb,
*inserted_head);
return (-1);
}
ap_ssi_parse_string(r, ctx, tag_val, parsed_string,
sizeof(parsed_string), 0);
parsed_string = ap_ssi_parse_string(r, ctx, tag_val, NULL,
MAX_STRING_LEN, 0);
apr_table_setn(r->subprocess_env, apr_pstrdup(r->pool, var),
apr_pstrdup(r->pool, parsed_string));
}

4
modules/filters/mod_include.h
View File

@@ -220,11 +220,11 @@ APR_DECLARE_OPTIONAL_FN(void, ap_ssi_get_tag_and_value, (include_ctx_t *ctx,
char **tag,
char **tag_val,
int dodecode));
APR_DECLARE_OPTIONAL_FN(void, ap_ssi_parse_string, (request_rec *r,
APR_DECLARE_OPTIONAL_FN(char*, ap_ssi_parse_string, (request_rec *r,
include_ctx_t *ctx,
const char *in,
char *out,
size_t length,
apr_size_t length,
int leave_name));
APR_DECLARE_OPTIONAL_FN(void, ap_register_include_handler,
(char *tag, include_handler_fn_t *func));