1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #include <grpc/support/port_platform.h>
20
21 #ifdef GPR_POSIX_STRING
22
23 #include <stdarg.h>
24 #include <stdio.h>
25 #include <string.h>
26
27 #include <grpc/support/alloc.h>
28 #include <grpc/support/string_util.h>
29
gpr_asprintf(char ** strp,const char * format,...)30 int gpr_asprintf(char** strp, const char* format, ...) {
31 va_list args;
32 int ret;
33 char buf[64];
34 size_t strp_buflen;
35
36 /* Use a constant-sized buffer to determine the length. */
37 va_start(args, format);
38 ret = vsnprintf(buf, sizeof(buf), format, args);
39 va_end(args);
40 if (ret < 0) {
41 *strp = nullptr;
42 return -1;
43 }
44
45 /* Allocate a new buffer, with space for the NUL terminator. */
46 strp_buflen = static_cast<size_t>(ret) + 1;
47 if ((*strp = static_cast<char*>(gpr_malloc(strp_buflen))) == nullptr) {
48 /* This shouldn't happen, because gpr_malloc() calls abort(). */
49 return -1;
50 }
51
52 /* Return early if we have all the bytes. */
53 if (strp_buflen <= sizeof(buf)) {
54 memcpy(*strp, buf, strp_buflen);
55 return ret;
56 }
57
58 /* Try again using the larger buffer. */
59 va_start(args, format);
60 ret = vsnprintf(*strp, strp_buflen, format, args);
61 va_end(args);
62 if (static_cast<size_t>(ret) == strp_buflen - 1) {
63 return ret;
64 }
65
66 /* This should never happen. */
67 gpr_free(*strp);
68 *strp = nullptr;
69 return -1;
70 }
71
72 #endif /* GPR_POSIX_STRING */
73