1 #include "stdio_impl.h"
2 #include <errno.h>
3 #include <string.h>
4 #include <stdlib.h>
5 #include <inttypes.h>
6 #include "libc.h"
7
8 struct cookie {
9 size_t pos, len, size;
10 unsigned char *buf;
11 int mode;
12 };
13
14 struct mem_FILE {
15 FILE f;
16 struct cookie c;
17 unsigned char buf[UNGET+BUFSIZ], buf2[];
18 };
19
mseek(FILE * f,off_t off,int whence)20 static off_t mseek(FILE *f, off_t off, int whence)
21 {
22 ssize_t base;
23 struct cookie *c = f->cookie;
24 if (whence>2U) {
25 fail:
26 errno = EINVAL;
27 return -1;
28 }
29 base = (size_t [3]){0, c->pos, c->len}[whence];
30 if (off < -base || off > (ssize_t)c->size-base) goto fail;
31 return c->pos = base+off;
32 }
33
mread(FILE * f,unsigned char * buf,size_t len)34 static size_t mread(FILE *f, unsigned char *buf, size_t len)
35 {
36 struct cookie *c = f->cookie;
37 size_t rem = c->len - c->pos;
38 if (c->pos > c->len) rem = 0;
39 if (len > rem) {
40 len = rem;
41 f->flags |= F_EOF;
42 }
43 memcpy(buf, c->buf+c->pos, len);
44 c->pos += len;
45 rem -= len;
46 if (rem > f->buf_size) rem = f->buf_size;
47 f->rpos = f->buf;
48 f->rend = f->buf + rem;
49 memcpy(f->rpos, c->buf+c->pos, rem);
50 c->pos += rem;
51 return len;
52 }
53
mwrite(FILE * f,const unsigned char * buf,size_t len)54 static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
55 {
56 struct cookie *c = f->cookie;
57 size_t rem;
58 size_t len2 = f->wpos - f->wbase;
59 if (len2) {
60 f->wpos = f->wbase;
61 if (mwrite(f, f->wpos, len2) < len2) return 0;
62 }
63 if (c->mode == 'a') c->pos = c->len;
64 rem = c->size - c->pos;
65 if (len > rem) len = rem;
66 memcpy(c->buf+c->pos, buf, len);
67 c->pos += len;
68 if (c->pos > c->len) {
69 c->len = c->pos;
70 if (c->len < c->size) c->buf[c->len] = 0;
71 else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0;
72 }
73 return len;
74 }
75
mclose(FILE * m)76 static int mclose(FILE *m)
77 {
78 return 0;
79 }
80
fmemopen(void * restrict buf,size_t size,const char * restrict mode)81 FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
82 {
83 struct mem_FILE *f;
84 int plus = !!strchr(mode, '+');
85
86 if (!strchr("rwa", *mode)) {
87 errno = EINVAL;
88 return 0;
89 }
90
91 if (!buf && size > PTRDIFF_MAX) {
92 errno = ENOMEM;
93 return 0;
94 }
95
96 f = malloc(sizeof *f + (buf?0:size));
97 if (!f) return 0;
98 memset(&f->f, 0, sizeof f->f);
99 f->f.cookie = &f->c;
100 f->f.fd = -1;
101 f->f.lbf = EOF;
102 f->f.buf = f->buf + UNGET;
103 f->f.buf_size = sizeof f->buf - UNGET;
104 if (!buf) {
105 buf = f->buf2;;
106 memset(buf, 0, size);
107 }
108
109 memset(&f->c, 0, sizeof f->c);
110 f->c.buf = buf;
111 f->c.size = size;
112 f->c.mode = *mode;
113
114 if (!plus) f->f.flags = (*mode == 'r') ? F_NOWR : F_NORD;
115 if (*mode == 'r') f->c.len = size;
116 else if (*mode == 'a') f->c.len = f->c.pos = strnlen(buf, size);
117 else if (plus) *f->c.buf = 0;
118
119 f->f.read = mread;
120 f->f.write = mwrite;
121 f->f.seek = mseek;
122 f->f.close = mclose;
123
124 if (!libc.threaded) f->f.lock = -1;
125
126 return __ofl_add(&f->f);
127 }
128