1 #include "stdio_impl.h"
2 #include <errno.h>
3 #include <limits.h>
4 #include <string.h>
5 #include <stdlib.h>
6 #include "libc.h"
7
8 struct cookie {
9 char **bufp;
10 size_t *sizep;
11 size_t pos;
12 char *buf;
13 size_t len;
14 size_t space;
15 };
16
17 struct ms_FILE {
18 FILE f;
19 struct cookie c;
20 unsigned char buf[BUFSIZ];
21 };
22
ms_seek(FILE * f,off_t off,int whence)23 static off_t ms_seek(FILE *f, off_t off, int whence)
24 {
25 ssize_t base;
26 struct cookie *c = f->cookie;
27 if (whence>2U) {
28 fail:
29 errno = EINVAL;
30 return -1;
31 }
32 base = (size_t [3]){0, c->pos, c->len}[whence];
33 if (off < -base || off > SSIZE_MAX-base) goto fail;
34 return c->pos = base+off;
35 }
36
ms_write(FILE * f,const unsigned char * buf,size_t len)37 static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
38 {
39 struct cookie *c = f->cookie;
40 size_t len2 = f->wpos - f->wbase;
41 char *newbuf;
42 if (len2) {
43 f->wpos = f->wbase;
44 if (ms_write(f, f->wbase, len2) < len2) return 0;
45 }
46 if (len + c->pos >= c->space) {
47 len2 = 2*c->space+1 | c->pos+len+1;
48 newbuf = realloc(c->buf, len2);
49 if (!newbuf) return 0;
50 *c->bufp = c->buf = newbuf;
51 memset(c->buf + c->space, 0, len2 - c->space);
52 c->space = len2;
53 }
54 memcpy(c->buf+c->pos, buf, len);
55 c->pos += len;
56 if (c->pos >= c->len) c->len = c->pos;
57 *c->sizep = c->pos;
58 return len;
59 }
60
ms_close(FILE * f)61 static int ms_close(FILE *f)
62 {
63 return 0;
64 }
65
open_memstream(char ** bufp,size_t * sizep)66 FILE *open_memstream(char **bufp, size_t *sizep)
67 {
68 struct ms_FILE *f;
69 char *buf;
70
71 if (!(f=malloc(sizeof *f))) return 0;
72 if (!(buf=malloc(sizeof *buf))) {
73 free(f);
74 return 0;
75 }
76 memset(&f->f, 0, sizeof f->f);
77 memset(&f->c, 0, sizeof f->c);
78 f->f.cookie = &f->c;
79
80 f->c.bufp = bufp;
81 f->c.sizep = sizep;
82 f->c.pos = f->c.len = f->c.space = *sizep = 0;
83 f->c.buf = *bufp = buf;
84 *buf = 0;
85
86 f->f.flags = F_NORD;
87 f->f.fd = -1;
88 f->f.buf = f->buf;
89 f->f.buf_size = sizeof f->buf;
90 f->f.lbf = EOF;
91 f->f.write = ms_write;
92 f->f.seek = ms_seek;
93 f->f.close = ms_close;
94 f->f.mode = -1;
95
96 if (!libc.threaded) f->f.lock = -1;
97
98 return __ofl_add(&f->f);
99 }
100