1 #include "stdio_impl.h"
2 #include <errno.h>
3 #include <string.h>
4 #include <stdlib.h>
5 #include <stddef.h>
6 #include <inttypes.h>
7 #include "libc.h"
8
9 struct cookie {
10 size_t pos, len, size;
11 unsigned char *buf;
12 int mode;
13 };
14
15 struct mem_FILE {
16 FILE f;
17 struct cookie c;
18 unsigned char buf[UNGET+BUFSIZ], buf2[];
19 };
20
mseek(FILE *f, off_t off, int whence)21 static off_t mseek(FILE *f, off_t off, int whence)
22 {
23 ssize_t base;
24 struct cookie *c = f->cookie;
25 if (whence>2U) {
26 fail:
27 errno = EINVAL;
28 return -1;
29 }
30 base = (size_t [3]){0, c->pos, c->len}[whence];
31 if (off < -base || off > (ssize_t)c->size-base) goto fail;
32 return c->pos = base+off;
33 }
34
mread(FILE *f, unsigned char *buf, size_t len)35 static size_t mread(FILE *f, unsigned char *buf, size_t len)
36 {
37 struct cookie *c = f->cookie;
38 size_t rem = c->len - c->pos;
39 if (c->pos > c->len) rem = 0;
40 if (len > rem) {
41 len = rem;
42 f->flags |= F_EOF;
43 }
44 memcpy(buf, c->buf+c->pos, len);
45 c->pos += len;
46 rem -= len;
47 if (rem > f->buf_size) rem = f->buf_size;
48 f->rpos = f->buf;
49 f->rend = f->buf + rem;
50 memcpy(f->rpos, c->buf+c->pos, rem);
51 c->pos += rem;
52 return len;
53 }
54
55 // We should not double fill f->buf when fread is filling buffer
mreadx(FILE *f, unsigned char *buf, size_t len)56 static size_t mreadx(FILE *f, unsigned char *buf, size_t len)
57 {
58 struct cookie *c = f->cookie;
59 size_t rem = c->len - c->pos;
60 if (c->pos > c->len) rem = 0;
61 if (len > rem) {
62 len = rem;
63 f->flags |= F_EOF;
64 }
65 memcpy(buf, c->buf+c->pos, len);
66 c->pos += len;
67 return len;
68 }
69
mwrite(FILE *f, const unsigned char *buf, size_t len)70 static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
71 {
72 struct cookie *c = f->cookie;
73 size_t rem;
74 size_t len2 = f->wpos - f->wbase;
75 if (len2) {
76 f->wpos = f->wbase;
77 if (mwrite(f, f->wpos, len2) < len2) return 0;
78 }
79 if (c->mode == 'a') c->pos = c->len;
80 rem = c->size - c->pos;
81 if (len > rem) len = rem;
82 memcpy(c->buf+c->pos, buf, len);
83 c->pos += len;
84 if (c->pos > c->len) {
85 c->len = c->pos;
86 if (c->len < c->size) c->buf[c->len] = 0;
87 else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0;
88 }
89 return len;
90 }
91
mclose(FILE *m)92 static int mclose(FILE *m)
93 {
94 return 0;
95 }
96
fmemopen(void *restrict buf, size_t size, const char *restrict mode)97 FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
98 {
99 struct mem_FILE *f;
100 int plus = !!strchr(mode, '+');
101
102 if (!strchr("rwa", *mode)) {
103 errno = EINVAL;
104 return 0;
105 }
106
107 if (!buf && size > PTRDIFF_MAX) {
108 errno = ENOMEM;
109 return 0;
110 }
111
112 f = malloc(sizeof *f + (buf?0:size));
113 if (!f) return 0;
114 memset(f, 0, offsetof(struct mem_FILE, buf));
115 f->f.cookie = &f->c;
116 f->f.fd = -1;
117 f->f.lbf = EOF;
118 f->f.buf = f->buf + UNGET;
119 f->f.buf_size = sizeof f->buf - UNGET;
120 if (!buf) {
121 buf = f->buf2;
122 memset(buf, 0, size);
123 }
124
125 f->c.buf = buf;
126 f->c.size = size;
127 f->c.mode = *mode;
128
129 if (!plus) f->f.flags = (*mode == 'r') ? F_NOWR : F_NORD;
130 if (*mode == 'r') f->c.len = size;
131 else if (*mode == 'a') f->c.len = f->c.pos = strnlen(buf, size);
132 else if (plus) *f->c.buf = 0;
133
134 f->f.read = mread;
135 f->f.readx = mreadx;
136 f->f.write = mwrite;
137 f->f.seek = mseek;
138 f->f.close = mclose;
139
140 if (!libc.threaded) f->f.lock = -1;
141
142 return __ofl_add(&f->f);
143 }
144