328 lines
7.8 KiB
C
328 lines
7.8 KiB
C
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/*
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* A git credential helper that interface with Windows' Credential Manager
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*
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*/
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#include <windows.h>
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#include <stdio.h>
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#include <io.h>
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#include <fcntl.h>
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/* common helpers */
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#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
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static void die(const char *err, ...)
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{
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char msg[4096];
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va_list params;
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va_start(params, err);
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vsnprintf(msg, sizeof(msg), err, params);
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fprintf(stderr, "%s\n", msg);
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va_end(params);
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exit(1);
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}
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static void *xmalloc(size_t size)
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{
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void *ret = malloc(size);
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if (!ret && !size)
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ret = malloc(1);
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if (!ret)
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die("Out of memory");
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return ret;
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}
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/* MinGW doesn't have wincred.h, so we need to define stuff */
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typedef struct _CREDENTIAL_ATTRIBUTEW {
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LPWSTR Keyword;
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DWORD Flags;
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DWORD ValueSize;
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LPBYTE Value;
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} CREDENTIAL_ATTRIBUTEW, *PCREDENTIAL_ATTRIBUTEW;
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typedef struct _CREDENTIALW {
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DWORD Flags;
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DWORD Type;
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LPWSTR TargetName;
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LPWSTR Comment;
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FILETIME LastWritten;
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DWORD CredentialBlobSize;
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LPBYTE CredentialBlob;
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DWORD Persist;
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DWORD AttributeCount;
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PCREDENTIAL_ATTRIBUTEW Attributes;
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LPWSTR TargetAlias;
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LPWSTR UserName;
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} CREDENTIALW, *PCREDENTIALW;
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#define CRED_TYPE_GENERIC 1
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#define CRED_PERSIST_LOCAL_MACHINE 2
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#define CRED_MAX_ATTRIBUTES 64
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typedef BOOL (WINAPI *CredWriteWT)(PCREDENTIALW, DWORD);
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typedef BOOL (WINAPI *CredEnumerateWT)(LPCWSTR, DWORD, DWORD *,
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PCREDENTIALW **);
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typedef VOID (WINAPI *CredFreeT)(PVOID);
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typedef BOOL (WINAPI *CredDeleteWT)(LPCWSTR, DWORD, DWORD);
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static HMODULE advapi;
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static CredWriteWT CredWriteW;
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static CredEnumerateWT CredEnumerateW;
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static CredFreeT CredFree;
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static CredDeleteWT CredDeleteW;
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static void load_cred_funcs(void)
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{
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/* load DLLs */
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advapi = LoadLibraryExA("advapi32.dll", NULL,
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LOAD_LIBRARY_SEARCH_SYSTEM32);
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if (!advapi)
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die("failed to load advapi32.dll");
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/* get function pointers */
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CredWriteW = (CredWriteWT)GetProcAddress(advapi, "CredWriteW");
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CredEnumerateW = (CredEnumerateWT)GetProcAddress(advapi,
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"CredEnumerateW");
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CredFree = (CredFreeT)GetProcAddress(advapi, "CredFree");
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CredDeleteW = (CredDeleteWT)GetProcAddress(advapi, "CredDeleteW");
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if (!CredWriteW || !CredEnumerateW || !CredFree || !CredDeleteW)
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die("failed to load functions");
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}
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static WCHAR *wusername, *password, *protocol, *host, *path, target[1024];
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static void write_item(const char *what, LPCWSTR wbuf, int wlen)
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{
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char *buf;
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if (!wbuf || !wlen) {
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printf("%s=\n", what);
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return;
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}
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int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, NULL, 0, NULL,
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FALSE);
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buf = xmalloc(len);
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if (!WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, buf, len, NULL, FALSE))
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die("WideCharToMultiByte failed!");
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printf("%s=", what);
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fwrite(buf, 1, len, stdout);
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putchar('\n');
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free(buf);
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}
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/*
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* Match an (optional) expected string and a delimiter in the target string,
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* consuming the matched text by updating the target pointer.
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*/
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static LPCWSTR wcsstr_last(LPCWSTR str, LPCWSTR find)
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{
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LPCWSTR res = NULL, pos;
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for (pos = wcsstr(str, find); pos; pos = wcsstr(pos + 1, find))
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res = pos;
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return res;
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}
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static int match_part_with_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim, int last)
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{
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LPCWSTR delim_pos, start = *ptarget;
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int len;
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/* find start of delimiter (or end-of-string if delim is empty) */
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if (*delim)
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delim_pos = last ? wcsstr_last(start, delim) : wcsstr(start, delim);
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else
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delim_pos = start + wcslen(start);
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/*
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* match text up to delimiter, or end of string (e.g. the '/' after
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* host is optional if not followed by a path)
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*/
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if (delim_pos)
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len = delim_pos - start;
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else
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len = wcslen(start);
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/* update ptarget if we either found a delimiter or need a match */
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if (delim_pos || want)
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*ptarget = delim_pos ? delim_pos + wcslen(delim) : start + len;
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return !want || (!wcsncmp(want, start, len) && !want[len]);
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}
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static int match_part(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
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{
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return match_part_with_last(ptarget, want, delim, 0);
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}
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static int match_part_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
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{
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return match_part_with_last(ptarget, want, delim, 1);
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}
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static int match_cred(const CREDENTIALW *cred)
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{
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LPCWSTR target = cred->TargetName;
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if (wusername && wcscmp(wusername, cred->UserName ? cred->UserName : L""))
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return 0;
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return match_part(&target, L"git", L":") &&
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match_part(&target, protocol, L"://") &&
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match_part_last(&target, wusername, L"@") &&
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match_part(&target, host, L"/") &&
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match_part(&target, path, L"");
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}
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static void get_credential(void)
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{
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CREDENTIALW **creds;
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DWORD num_creds;
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int i;
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if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
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return;
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/* search for the first credential that matches username */
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for (i = 0; i < num_creds; ++i)
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if (match_cred(creds[i])) {
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write_item("username", creds[i]->UserName,
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creds[i]->UserName ? wcslen(creds[i]->UserName) : 0);
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write_item("password",
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(LPCWSTR)creds[i]->CredentialBlob,
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creds[i]->CredentialBlobSize / sizeof(WCHAR));
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break;
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}
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CredFree(creds);
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}
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static void store_credential(void)
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{
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CREDENTIALW cred;
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if (!wusername || !password)
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return;
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cred.Flags = 0;
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cred.Type = CRED_TYPE_GENERIC;
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cred.TargetName = target;
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cred.Comment = L"saved by git-credential-wincred";
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cred.CredentialBlobSize = (wcslen(password)) * sizeof(WCHAR);
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cred.CredentialBlob = (LPVOID)password;
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cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
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cred.AttributeCount = 0;
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cred.Attributes = NULL;
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cred.TargetAlias = NULL;
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cred.UserName = wusername;
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if (!CredWriteW(&cred, 0))
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die("CredWrite failed");
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}
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static void erase_credential(void)
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{
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CREDENTIALW **creds;
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DWORD num_creds;
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int i;
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if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
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return;
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for (i = 0; i < num_creds; ++i) {
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if (match_cred(creds[i]))
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CredDeleteW(creds[i]->TargetName, creds[i]->Type, 0);
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}
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CredFree(creds);
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}
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static WCHAR *utf8_to_utf16_dup(const char *str)
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{
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int wlen = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
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WCHAR *wstr = xmalloc(sizeof(WCHAR) * wlen);
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MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, wlen);
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return wstr;
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}
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static void read_credential(void)
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{
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char buf[1024];
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while (fgets(buf, sizeof(buf), stdin)) {
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char *v;
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int len = strlen(buf);
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/* strip trailing CR / LF */
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while (len && strchr("\r\n", buf[len - 1]))
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buf[--len] = 0;
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if (!*buf)
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break;
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v = strchr(buf, '=');
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if (!v)
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die("bad input: %s", buf);
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*v++ = '\0';
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if (!strcmp(buf, "protocol"))
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protocol = utf8_to_utf16_dup(v);
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else if (!strcmp(buf, "host"))
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host = utf8_to_utf16_dup(v);
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else if (!strcmp(buf, "path"))
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path = utf8_to_utf16_dup(v);
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else if (!strcmp(buf, "username")) {
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wusername = utf8_to_utf16_dup(v);
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} else if (!strcmp(buf, "password"))
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password = utf8_to_utf16_dup(v);
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else
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die("unrecognized input");
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}
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}
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int main(int argc, char *argv[])
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{
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const char *usage =
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"usage: git credential-wincred <get|store|erase>\n";
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if (!argv[1])
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die(usage);
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/* git use binary pipes to avoid CRLF-issues */
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_setmode(_fileno(stdin), _O_BINARY);
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_setmode(_fileno(stdout), _O_BINARY);
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read_credential();
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load_cred_funcs();
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if (!protocol || !(host || path))
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return 0;
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/* prepare 'target', the unique key for the credential */
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wcscpy(target, L"git:");
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wcsncat(target, protocol, ARRAY_SIZE(target));
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wcsncat(target, L"://", ARRAY_SIZE(target));
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if (wusername) {
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wcsncat(target, wusername, ARRAY_SIZE(target));
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wcsncat(target, L"@", ARRAY_SIZE(target));
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}
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if (host)
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wcsncat(target, host, ARRAY_SIZE(target));
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if (path) {
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wcsncat(target, L"/", ARRAY_SIZE(target));
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wcsncat(target, path, ARRAY_SIZE(target));
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}
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if (!strcmp(argv[1], "get"))
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get_credential();
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else if (!strcmp(argv[1], "store"))
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store_credential();
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else if (!strcmp(argv[1], "erase"))
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erase_credential();
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/* otherwise, ignore unknown action */
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return 0;
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}
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