xref: /aosp_15_r20/external/musl/src/stdio/fgets.c (revision c9945492fdd68bbe62686c5b452b4dc1be3f8453)
1*c9945492SAndroid Build Coastguard Worker #include "stdio_impl.h"
2*c9945492SAndroid Build Coastguard Worker #include <string.h>
3*c9945492SAndroid Build Coastguard Worker 
4*c9945492SAndroid Build Coastguard Worker #define MIN(a,b) ((a)<(b) ? (a) : (b))
5*c9945492SAndroid Build Coastguard Worker 
fgets(char * restrict s,int n,FILE * restrict f)6*c9945492SAndroid Build Coastguard Worker char *fgets(char *restrict s, int n, FILE *restrict f)
7*c9945492SAndroid Build Coastguard Worker {
8*c9945492SAndroid Build Coastguard Worker 	char *p = s;
9*c9945492SAndroid Build Coastguard Worker 	unsigned char *z;
10*c9945492SAndroid Build Coastguard Worker 	size_t k;
11*c9945492SAndroid Build Coastguard Worker 	int c;
12*c9945492SAndroid Build Coastguard Worker 
13*c9945492SAndroid Build Coastguard Worker 	FLOCK(f);
14*c9945492SAndroid Build Coastguard Worker 
15*c9945492SAndroid Build Coastguard Worker 	if (n<=1) {
16*c9945492SAndroid Build Coastguard Worker 		f->mode |= f->mode-1;
17*c9945492SAndroid Build Coastguard Worker 		FUNLOCK(f);
18*c9945492SAndroid Build Coastguard Worker 		if (n<1) return 0;
19*c9945492SAndroid Build Coastguard Worker 		*s = 0;
20*c9945492SAndroid Build Coastguard Worker 		return s;
21*c9945492SAndroid Build Coastguard Worker 	}
22*c9945492SAndroid Build Coastguard Worker 	n--;
23*c9945492SAndroid Build Coastguard Worker 
24*c9945492SAndroid Build Coastguard Worker 	while (n) {
25*c9945492SAndroid Build Coastguard Worker 		if (f->rpos != f->rend) {
26*c9945492SAndroid Build Coastguard Worker 			z = memchr(f->rpos, '\n', f->rend - f->rpos);
27*c9945492SAndroid Build Coastguard Worker 			k = z ? z - f->rpos + 1 : f->rend - f->rpos;
28*c9945492SAndroid Build Coastguard Worker 			k = MIN(k, n);
29*c9945492SAndroid Build Coastguard Worker 			memcpy(p, f->rpos, k);
30*c9945492SAndroid Build Coastguard Worker 			f->rpos += k;
31*c9945492SAndroid Build Coastguard Worker 			p += k;
32*c9945492SAndroid Build Coastguard Worker 			n -= k;
33*c9945492SAndroid Build Coastguard Worker 			if (z || !n) break;
34*c9945492SAndroid Build Coastguard Worker 		}
35*c9945492SAndroid Build Coastguard Worker 		if ((c = getc_unlocked(f)) < 0) {
36*c9945492SAndroid Build Coastguard Worker 			if (p==s || !feof(f)) s = 0;
37*c9945492SAndroid Build Coastguard Worker 			break;
38*c9945492SAndroid Build Coastguard Worker 		}
39*c9945492SAndroid Build Coastguard Worker 		n--;
40*c9945492SAndroid Build Coastguard Worker 		if ((*p++ = c) == '\n') break;
41*c9945492SAndroid Build Coastguard Worker 	}
42*c9945492SAndroid Build Coastguard Worker 	if (s) *p = 0;
43*c9945492SAndroid Build Coastguard Worker 
44*c9945492SAndroid Build Coastguard Worker 	FUNLOCK(f);
45*c9945492SAndroid Build Coastguard Worker 
46*c9945492SAndroid Build Coastguard Worker 	return s;
47*c9945492SAndroid Build Coastguard Worker }
48*c9945492SAndroid Build Coastguard Worker 
49*c9945492SAndroid Build Coastguard Worker weak_alias(fgets, fgets_unlocked);
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