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git/http.h
Jeff King 188923f0d1 http: fix segfault in handle_curl_result 
When we create an http active_request_slot, we can set its
"results" pointer back to local storage. The http code will
fill in the details of how the request went, and we can
access those details even after the slot has been cleaned
up.

Commit 8809703 (http: factor out http error code handling)
switched us from accessing our local results struct directly
to accessing it via the "results" pointer of the slot. That
means we're accessing the slot after it has been marked as
finished, defeating the whole purpose of keeping the results
storage separate.

Most of the time this doesn't matter, as finishing the slot
does not actually clean up the pointer. However, when using
curl's multi interface with the dumb-http revision walker,
we might actually start a new request before handing control
back to the original caller. In that case, we may reuse the
slot, zeroing its results pointer, and leading the original
caller to segfault while looking for its results inside the
slot.

Instead, we need to pass a pointer to our local results
storage to the handle_curl_result function, rather than
relying on the pointer in the slot struct. This matches what
the original code did before the refactoring (which did not
use a separate function, and therefore just accessed the
results struct directly).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-10-12 09:42:31 -07:00

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#ifndef HTTP_H
#define HTTP_H
#include "cache.h"
#include <curl/curl.h>
#include <curl/easy.h>
#include "strbuf.h"
#include "remote.h"
#include "url.h"
/*
* We detect based on the cURL version if multi-transfer is
* usable in this implementation and define this symbol accordingly.
* This is not something Makefile should set nor users should pass
* via CFLAGS.
*/
#undef USE_CURL_MULTI
#if LIBCURL_VERSION_NUM >= 0x071000
#define USE_CURL_MULTI
#define DEFAULT_MAX_REQUESTS 5
#endif
#if LIBCURL_VERSION_NUM < 0x070704
#define curl_global_cleanup() do { /* nothing */ } while (0)
#endif
#if LIBCURL_VERSION_NUM < 0x070800
#define curl_global_init(a) do { /* nothing */ } while (0)
#endif
#if (LIBCURL_VERSION_NUM < 0x070c04) || (LIBCURL_VERSION_NUM == 0x071000)
#define NO_CURL_EASY_DUPHANDLE
#endif
#if LIBCURL_VERSION_NUM < 0x070a03
#define CURLE_HTTP_RETURNED_ERROR CURLE_HTTP_NOT_FOUND
#endif
#if LIBCURL_VERSION_NUM < 0x070c03
#define NO_CURL_IOCTL
#endif
struct slot_results {
CURLcode curl_result;
long http_code;
};
struct active_request_slot {
CURL *curl;
int in_use;
CURLcode curl_result;
long http_code;
int *finished;
struct slot_results *results;
void *callback_data;
void (*callback_func)(void *data);
struct active_request_slot *next;
};
struct buffer {
struct strbuf buf;
size_t posn;
};
/* Curl request read/write callbacks */
extern size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *strbuf);
extern size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *strbuf);
extern size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf);
#ifndef NO_CURL_IOCTL
extern curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp);
#endif
/* Slot lifecycle functions */
extern struct active_request_slot *get_active_slot(void);
extern int start_active_slot(struct active_request_slot *slot);
extern void run_active_slot(struct active_request_slot *slot);
extern void finish_active_slot(struct active_request_slot *slot);
extern void finish_all_active_slots(void);
extern int handle_curl_result(struct active_request_slot *slot,
struct slot_results *results);
#ifdef USE_CURL_MULTI
extern void fill_active_slots(void);
extern void add_fill_function(void *data, int (*fill)(void *));
extern void step_active_slots(void);
#endif
extern void http_init(struct remote *remote, const char *url,
int proactive_auth);
extern void http_cleanup(void);
extern int active_requests;
extern int http_is_verbose;
extern size_t http_post_buffer;
extern char curl_errorstr[CURL_ERROR_SIZE];
static inline int missing__target(int code, int result)
{
return /* file:// URL -- do we ever use one??? */
(result == CURLE_FILE_COULDNT_READ_FILE) ||
/* http:// and https:// URL */
(code == 404 && result == CURLE_HTTP_RETURNED_ERROR) ||
/* ftp:// URL */
(code == 550 && result == CURLE_FTP_COULDNT_RETR_FILE)
;
}
#define missing_target(a) missing__target((a)->http_code, (a)->curl_result)
/* Helpers for modifying and creating URLs */
extern void append_remote_object_url(struct strbuf *buf, const char *url,
const char *hex,
int only_two_digit_prefix);
extern char *get_remote_object_url(const char *url, const char *hex,
int only_two_digit_prefix);
/* Options for http_request_*() */
#define HTTP_NO_CACHE 1
/* Return values for http_request_*() */
#define HTTP_OK 0
#define HTTP_MISSING_TARGET 1
#define HTTP_ERROR 2
#define HTTP_START_FAILED 3
#define HTTP_REAUTH 4
#define HTTP_NOAUTH 5
/*
* Requests a URL and stores the result in a strbuf.
*
* If the result pointer is NULL, a HTTP HEAD request is made instead of GET.
*/
int http_get_strbuf(const char *url, struct strbuf *result, int options);
/*
* Prints an error message using error() containing url and curl_errorstr,
* and returns ret.
*/
int http_error(const char *url, int ret);
extern int http_fetch_ref(const char *base, struct ref *ref);
/* Helpers for fetching packs */
extern int http_get_info_packs(const char *base_url,
struct packed_git **packs_head);
struct http_pack_request {
char *url;
struct packed_git *target;
struct packed_git **lst;
FILE *packfile;
char tmpfile[PATH_MAX];
struct curl_slist *range_header;
struct active_request_slot *slot;
};
extern struct http_pack_request *new_http_pack_request(
struct packed_git *target, const char *base_url);
extern int finish_http_pack_request(struct http_pack_request *preq);
extern void release_http_pack_request(struct http_pack_request *preq);
/* Helpers for fetching object */
struct http_object_request {
char *url;
char tmpfile[PATH_MAX];
int localfile;
CURLcode curl_result;
char errorstr[CURL_ERROR_SIZE];
long http_code;
unsigned char sha1[20];
unsigned char real_sha1[20];
git_SHA_CTX c;
git_zstream stream;
int zret;
int rename;
struct active_request_slot *slot;
};
extern struct http_object_request *new_http_object_request(
const char *base_url, unsigned char *sha1);
extern void process_http_object_request(struct http_object_request *freq);
extern int finish_http_object_request(struct http_object_request *freq);
extern void abort_http_object_request(struct http_object_request *freq);
extern void release_http_object_request(struct http_object_request *freq);
#endif /* HTTP_H */
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