xref: /inferno-os/libkern/vsmprint.c (revision 871e0f01ca6cdef953c81d1a5018d90fbd01838a)
1 /*
2  * The authors of this software are Rob Pike and Ken Thompson.
3  *              Copyright (c) 2002 by Lucent Technologies.
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose without fee is hereby granted, provided that this entire notice
6  * is included in all copies of any software which is or includes a copy
7  * or modification of this software and in all copies of the supporting
8  * documentation for such software.
9  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
10  * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
11  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
12  * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
13  */
14 #include "lib9.h"
15 #include "fmtdef.h"
16 
17 static int
18 fmtStrFlush(Fmt *f)
19 {
20 	char *s;
21 	int n;
22 
23 	if(f->start == nil)
24 		return 0;
25 	n = (int)f->farg;
26 	n += 256;
27 	f->farg = (void*)n;
28 	s = f->start;
29 	f->start = realloc(s, n);
30 	if(f->start == nil){
31 		free(s);
32 		f->to = nil;
33 		f->stop = nil;
34 		return 0;
35 	}
36 	f->to = (char*)f->start + ((char*)f->to - s);
37 	f->stop = (char*)f->start + n - 1;
38 	return 1;
39 }
40 
41 int
42 fmtstrinit(Fmt *f)
43 {
44 	int n;
45 
46 	memset(f, 0, sizeof(*f));
47 	n = 32;
48 	f->start = malloc(n);
49 	if(f->start == nil)
50 		return -1;
51 	f->to = f->start;
52 	f->stop = (char*)f->start + n - 1;
53 	f->flush = fmtStrFlush;
54 	f->farg = (void*)n;
55 	f->nfmt = 0;
56 	return 0;
57 }
58 
59 /*
60  * print into an allocated string buffer
61  */
62 char*
63 vsmprint(char *fmt, va_list args)
64 {
65 	Fmt f;
66 	int n;
67 
68 	if(fmtstrinit(&f) < 0)
69 		return nil;
70 	va_copy(f.args, args);
71 	n = dofmt(&f, fmt);
72 	va_end(f.args);
73 	if(n < 0){
74 		free(f.start);
75 		f.start = nil;
76 		return nil;
77 	}
78 	return fmtstrflush(&f);
79 }
80