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![Erik E Brady](/assets/img/avatar_default.png)
The credential subsystem can trigger SIGPIPE when writing to an external helper if that helper closes its stdin before reading the whole input. Normally this is rare, since helpers would need to read that input to make a decision about how to respond, but: 1. It's reasonable to configure a helper which only handles "get" while ignoring "store". Such a handler might not read stdin for "store", thereby rapidly closing stdin upon helper exit. 2. A broken or misbehaving helper might exit immediately. That's an error, but it's not reasonable for it to take down the parent Git process with SIGPIPE. Even with such a helper, seeing this problem should be rare. Getting SIGPIPE requires the helper racily exiting before we've written the fairly small credential output. Signed-off-by: Erik E Brady <brady@cisco.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
375 lines
7.9 KiB
C
375 lines
7.9 KiB
C
#include "cache.h"
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#include "config.h"
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#include "credential.h"
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#include "string-list.h"
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#include "run-command.h"
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#include "url.h"
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#include "prompt.h"
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#include "sigchain.h"
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void credential_init(struct credential *c)
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{
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memset(c, 0, sizeof(*c));
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c->helpers.strdup_strings = 1;
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}
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void credential_clear(struct credential *c)
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{
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free(c->protocol);
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free(c->host);
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free(c->path);
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free(c->username);
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free(c->password);
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string_list_clear(&c->helpers, 0);
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credential_init(c);
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}
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int credential_match(const struct credential *want,
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const struct credential *have)
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{
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#define CHECK(x) (!want->x || (have->x && !strcmp(want->x, have->x)))
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return CHECK(protocol) &&
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CHECK(host) &&
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CHECK(path) &&
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CHECK(username);
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#undef CHECK
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}
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static int credential_config_callback(const char *var, const char *value,
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void *data)
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{
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struct credential *c = data;
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const char *key, *dot;
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if (!skip_prefix(var, "credential.", &key))
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return 0;
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if (!value)
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return config_error_nonbool(var);
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dot = strrchr(key, '.');
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if (dot) {
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struct credential want = CREDENTIAL_INIT;
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char *url = xmemdupz(key, dot - key);
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int matched;
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credential_from_url(&want, url);
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matched = credential_match(&want, c);
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credential_clear(&want);
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free(url);
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if (!matched)
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return 0;
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key = dot + 1;
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}
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if (!strcmp(key, "helper")) {
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if (*value)
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string_list_append(&c->helpers, value);
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else
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string_list_clear(&c->helpers, 0);
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} else if (!strcmp(key, "username")) {
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if (!c->username)
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c->username = xstrdup(value);
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}
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else if (!strcmp(key, "usehttppath"))
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c->use_http_path = git_config_bool(var, value);
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return 0;
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}
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static int proto_is_http(const char *s)
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{
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if (!s)
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return 0;
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return !strcmp(s, "https") || !strcmp(s, "http");
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}
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static void credential_apply_config(struct credential *c)
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{
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if (c->configured)
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return;
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git_config(credential_config_callback, c);
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c->configured = 1;
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if (!c->use_http_path && proto_is_http(c->protocol)) {
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FREE_AND_NULL(c->path);
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}
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}
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static void credential_describe(struct credential *c, struct strbuf *out)
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{
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if (!c->protocol)
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return;
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strbuf_addf(out, "%s://", c->protocol);
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if (c->username && *c->username)
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strbuf_addf(out, "%s@", c->username);
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if (c->host)
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strbuf_addstr(out, c->host);
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if (c->path)
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strbuf_addf(out, "/%s", c->path);
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}
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static char *credential_ask_one(const char *what, struct credential *c,
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int flags)
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{
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struct strbuf desc = STRBUF_INIT;
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struct strbuf prompt = STRBUF_INIT;
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char *r;
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credential_describe(c, &desc);
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if (desc.len)
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strbuf_addf(&prompt, "%s for '%s': ", what, desc.buf);
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else
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strbuf_addf(&prompt, "%s: ", what);
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r = git_prompt(prompt.buf, flags);
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strbuf_release(&desc);
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strbuf_release(&prompt);
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return xstrdup(r);
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}
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static void credential_getpass(struct credential *c)
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{
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if (!c->username)
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c->username = credential_ask_one("Username", c,
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PROMPT_ASKPASS|PROMPT_ECHO);
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if (!c->password)
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c->password = credential_ask_one("Password", c,
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PROMPT_ASKPASS);
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}
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int credential_read(struct credential *c, FILE *fp)
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{
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struct strbuf line = STRBUF_INIT;
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while (strbuf_getline_lf(&line, fp) != EOF) {
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char *key = line.buf;
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char *value = strchr(key, '=');
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if (!line.len)
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break;
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if (!value) {
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warning("invalid credential line: %s", key);
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strbuf_release(&line);
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return -1;
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}
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*value++ = '\0';
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if (!strcmp(key, "username")) {
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free(c->username);
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c->username = xstrdup(value);
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} else if (!strcmp(key, "password")) {
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free(c->password);
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c->password = xstrdup(value);
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} else if (!strcmp(key, "protocol")) {
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free(c->protocol);
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c->protocol = xstrdup(value);
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} else if (!strcmp(key, "host")) {
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free(c->host);
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c->host = xstrdup(value);
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} else if (!strcmp(key, "path")) {
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free(c->path);
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c->path = xstrdup(value);
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} else if (!strcmp(key, "url")) {
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credential_from_url(c, value);
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} else if (!strcmp(key, "quit")) {
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c->quit = !!git_config_bool("quit", value);
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}
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/*
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* Ignore other lines; we don't know what they mean, but
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* this future-proofs us when later versions of git do
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* learn new lines, and the helpers are updated to match.
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*/
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}
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strbuf_release(&line);
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return 0;
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}
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static void credential_write_item(FILE *fp, const char *key, const char *value)
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{
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if (!value)
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return;
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fprintf(fp, "%s=%s\n", key, value);
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}
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void credential_write(const struct credential *c, FILE *fp)
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{
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credential_write_item(fp, "protocol", c->protocol);
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credential_write_item(fp, "host", c->host);
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credential_write_item(fp, "path", c->path);
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credential_write_item(fp, "username", c->username);
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credential_write_item(fp, "password", c->password);
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}
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static int run_credential_helper(struct credential *c,
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const char *cmd,
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int want_output)
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{
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struct child_process helper = CHILD_PROCESS_INIT;
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const char *argv[] = { NULL, NULL };
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FILE *fp;
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argv[0] = cmd;
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helper.argv = argv;
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helper.use_shell = 1;
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helper.in = -1;
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if (want_output)
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helper.out = -1;
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else
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helper.no_stdout = 1;
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if (start_command(&helper) < 0)
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return -1;
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fp = xfdopen(helper.in, "w");
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sigchain_push(SIGPIPE, SIG_IGN);
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credential_write(c, fp);
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fclose(fp);
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sigchain_pop(SIGPIPE);
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if (want_output) {
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int r;
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fp = xfdopen(helper.out, "r");
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r = credential_read(c, fp);
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fclose(fp);
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if (r < 0) {
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finish_command(&helper);
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return -1;
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}
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}
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if (finish_command(&helper))
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return -1;
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return 0;
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}
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static int credential_do(struct credential *c, const char *helper,
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const char *operation)
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{
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struct strbuf cmd = STRBUF_INIT;
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int r;
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if (helper[0] == '!')
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strbuf_addstr(&cmd, helper + 1);
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else if (is_absolute_path(helper))
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strbuf_addstr(&cmd, helper);
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else
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strbuf_addf(&cmd, "git credential-%s", helper);
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strbuf_addf(&cmd, " %s", operation);
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r = run_credential_helper(c, cmd.buf, !strcmp(operation, "get"));
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strbuf_release(&cmd);
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return r;
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}
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void credential_fill(struct credential *c)
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{
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int i;
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if (c->username && c->password)
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return;
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credential_apply_config(c);
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for (i = 0; i < c->helpers.nr; i++) {
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credential_do(c, c->helpers.items[i].string, "get");
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if (c->username && c->password)
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return;
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if (c->quit)
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die("credential helper '%s' told us to quit",
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c->helpers.items[i].string);
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}
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credential_getpass(c);
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if (!c->username && !c->password)
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die("unable to get password from user");
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}
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void credential_approve(struct credential *c)
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{
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int i;
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if (c->approved)
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return;
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if (!c->username || !c->password)
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return;
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credential_apply_config(c);
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for (i = 0; i < c->helpers.nr; i++)
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credential_do(c, c->helpers.items[i].string, "store");
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c->approved = 1;
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}
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void credential_reject(struct credential *c)
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{
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int i;
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credential_apply_config(c);
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for (i = 0; i < c->helpers.nr; i++)
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credential_do(c, c->helpers.items[i].string, "erase");
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FREE_AND_NULL(c->username);
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FREE_AND_NULL(c->password);
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c->approved = 0;
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}
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void credential_from_url(struct credential *c, const char *url)
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{
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const char *at, *colon, *cp, *slash, *host, *proto_end;
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credential_clear(c);
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/*
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* Match one of:
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* (1) proto://<host>/...
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* (2) proto://<user>@<host>/...
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* (3) proto://<user>:<pass>@<host>/...
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*/
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proto_end = strstr(url, "://");
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if (!proto_end)
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return;
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cp = proto_end + 3;
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at = strchr(cp, '@');
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colon = strchr(cp, ':');
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slash = strchrnul(cp, '/');
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if (!at || slash <= at) {
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/* Case (1) */
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host = cp;
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}
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else if (!colon || at <= colon) {
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/* Case (2) */
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c->username = url_decode_mem(cp, at - cp);
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host = at + 1;
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} else {
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/* Case (3) */
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c->username = url_decode_mem(cp, colon - cp);
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c->password = url_decode_mem(colon + 1, at - (colon + 1));
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host = at + 1;
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}
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if (proto_end - url > 0)
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c->protocol = xmemdupz(url, proto_end - url);
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if (slash - host > 0)
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c->host = url_decode_mem(host, slash - host);
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/* Trim leading and trailing slashes from path */
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while (*slash == '/')
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slash++;
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if (*slash) {
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char *p;
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c->path = url_decode(slash);
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p = c->path + strlen(c->path) - 1;
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while (p > c->path && *p == '/')
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*p-- = '\0';
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}
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}
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