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![Jeff King](/assets/img/avatar_default.png)
There are a few places in git that need to get a username and password credential from the user; the most notable one is HTTP authentication for smart-http pushing. Right now the only choices for providing credentials are to put them plaintext into your ~/.netrc, or to have git prompt you (either on the terminal or via an askpass program). The former is not very secure, and the latter is not very convenient. Unfortunately, there is no "always best" solution for password management. The details will depend on the tradeoff you want between security and convenience, as well as how git can integrate with other security systems (e.g., many operating systems provide a keychain or password wallet for single sign-on). This patch provides an abstract notion of credentials as a data item, and provides three basic operations: - fill (i.e., acquire from external storage or from the user) - approve (mark a credential as "working" for further storage) - reject (mark a credential as "not working", so it can be removed from storage) These operations can be backed by external helper processes that interact with system- or user-specific secure storage. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
235 lines
5 KiB
C
235 lines
5 KiB
C
#include "cache.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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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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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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{
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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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/* FIXME: for usernames, we should do something less magical that
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* actually echoes the characters. However, we need to read from
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* /dev/tty and not stdio, which is not portable (but getpass will do
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* it for us). http.c uses the same workaround. */
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r = git_getpass(prompt.buf);
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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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if (!c->password)
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c->password = credential_ask_one("Password", c);
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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(&line, fp, '\n') != 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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}
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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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static 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;
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const char *argv[] = { NULL, NULL };
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FILE *fp;
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memset(&helper, 0, sizeof(helper));
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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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credential_write(c, fp);
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fclose(fp);
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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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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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}
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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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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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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(c->username);
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c->username = NULL;
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free(c->password);
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c->password = NULL;
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c->approved = 0;
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}
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