1 #include "stdio_impl.h"
2 #include <errno.h>
3 #include <limits.h>
4 #include <string.h>
5
6 struct cookie {
7 char** bufp;
8 size_t* sizep;
9 size_t pos;
10 char* buf;
11 size_t len;
12 size_t space;
13 };
14
ms_seek(FILE * f,off_t off,int whence)15 static off_t ms_seek(FILE* f, off_t off, int whence) {
16 ssize_t base;
17 struct cookie* c = f->cookie;
18 if (whence > 2U) {
19 fail:
20 errno = EINVAL;
21 return -1;
22 }
23 base = (size_t[3]){0, c->pos, c->len}[whence];
24 if (off < -base || off > SSIZE_MAX - base)
25 goto fail;
26 return c->pos = base + off;
27 }
28
ms_write(FILE * f,const unsigned char * buf,size_t len)29 static size_t ms_write(FILE* f, const unsigned char* buf, size_t len) {
30 struct cookie* c = f->cookie;
31 size_t len2 = f->wpos - f->wbase;
32 char* newbuf;
33 if (len2) {
34 f->wpos = f->wbase;
35 if (ms_write(f, f->wbase, len2) < len2)
36 return 0;
37 }
38 if (len + c->pos >= c->space) {
39 len2 = (2 * c->space + 1) | (c->pos + len + 1);
40 newbuf = realloc(c->buf, len2);
41 if (!newbuf)
42 return 0;
43 *c->bufp = c->buf = newbuf;
44 memset(c->buf + c->space, 0, len2 - c->space);
45 c->space = len2;
46 }
47 memcpy(c->buf + c->pos, buf, len);
48 c->pos += len;
49 if (c->pos >= c->len)
50 c->len = c->pos;
51 *c->sizep = c->pos;
52 return len;
53 }
54
ms_close(FILE * f)55 static int ms_close(FILE* f) {
56 return 0;
57 }
58
open_memstream(char ** bufp,size_t * sizep)59 FILE* open_memstream(char** bufp, size_t* sizep) {
60 FILE* f;
61 struct cookie* c;
62 char* buf;
63
64 if (!(f = malloc(sizeof *f + sizeof *c + BUFSIZ)))
65 return 0;
66 if (!(buf = malloc(sizeof *buf))) {
67 free(f);
68 return 0;
69 }
70 memset(f, 0, sizeof *f + sizeof *c);
71 f->cookie = c = (void*)(f + 1);
72
73 c->bufp = bufp;
74 c->sizep = sizep;
75 c->pos = c->len = c->space = *sizep = 0;
76 c->buf = *bufp = buf;
77 *buf = 0;
78
79 f->flags = F_NORD;
80 f->fd = -1;
81 f->buf = (void*)(c + 1);
82 f->buf_size = BUFSIZ;
83 f->lbf = EOF;
84 f->write = ms_write;
85 f->seek = ms_seek;
86 f->close = ms_close;
87
88 return __ofl_add(f);
89 }
90