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 <grpc/support/alloc.h>
24 #include <grpc/support/string_util.h>
25 #include <stdarg.h>
26 #include <stdio.h>
27 #include <string.h>
28
gpr_asprintf(char ** strp,const char * format,...)29 int gpr_asprintf(char** strp, const char* format, ...) {
30 va_list args;
31 int ret;
32 char buf[64];
33 size_t strp_buflen;
34
35 // Use a constant-sized buffer to determine the length.
36 va_start(args, format);
37 ret = vsnprintf(buf, sizeof(buf), format, args);
38 va_end(args);
39 if (ret < 0) {
40 *strp = nullptr;
41 return -1;
42 }
43
44 // Allocate a new buffer, with space for the NUL terminator.
45 strp_buflen = static_cast<size_t>(ret) + 1;
46 if ((*strp = static_cast<char*>(gpr_malloc(strp_buflen))) == nullptr) {
47 // This shouldn't happen, because gpr_malloc() calls abort().
48 return -1;
49 }
50
51 // Return early if we have all the bytes.
52 if (strp_buflen <= sizeof(buf)) {
53 memcpy(*strp, buf, strp_buflen);
54 return ret;
55 }
56
57 // Try again using the larger buffer.
58 va_start(args, format);
59 ret = vsnprintf(*strp, strp_buflen, format, args);
60 va_end(args);
61 if (static_cast<size_t>(ret) == strp_buflen - 1) {
62 return ret;
63 }
64
65 // This should never happen.
66 gpr_free(*strp);
67 *strp = nullptr;
68 return -1;
69 }
70
71 #endif // GPR_POSIX_STRING
72