1/* printf implementation for the dynamic loader.
2 Copyright (C) 1997-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <_itoa.h>
20#include <assert.h>
21#include <dl-writev.h>
22#include <ldsodefs.h>
23#include <limits.h>
24#include <stdarg.h>
25#include <stdint.h>
26#include <stdlib.h>
27#include <string.h>
28#include <sys/uio.h>
29#include <unistd.h>
30#include <intprops.h>
31
32/* Bare-bones printf implementation. This function only knows about
33 the formats and flags needed and can handle only up to 64 stripes in
34 the output. */
35static void
36_dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
37{
38# define NIOVMAX 64
39 struct iovec iov[NIOVMAX];
40 /* Maximum size for 'd', 'u', and 'x' including padding. */
41 enum { IFMTSIZE = INT_STRLEN_BOUND(void *) };
42 char ifmtbuf[NIOVMAX][IFMTSIZE];
43 int niov = 0;
44 pid_t pid = 0;
45 char pidbuf[12];
46
47 while (*fmt != '\0')
48 {
49 const char *startp = fmt;
50
51 if (tag_p > 0)
52 {
53 /* Generate the tag line once. It consists of the PID and a
54 colon followed by a tab. */
55 if (pid == 0)
56 {
57 char *p;
58 pid = __getpid ();
59 assert (pid >= 0 && sizeof (pid_t) <= 4);
60 p = _itoa (pid, &pidbuf[10], 10, 0);
61 while (p > pidbuf)
62 *--p = ' ';
63 pidbuf[10] = ':';
64 pidbuf[11] = '\t';
65 }
66
67 /* Append to the output. */
68 assert (niov < NIOVMAX);
69 iov[niov].iov_len = 12;
70 iov[niov++].iov_base = pidbuf;
71
72 /* No more tags until we see the next newline. */
73 tag_p = -1;
74 }
75
76 /* Skip everything except % and \n (if tags are needed). */
77 while (*fmt != '\0' && *fmt != '%' && (! tag_p || *fmt != '\n'))
78 ++fmt;
79
80 /* Append constant string. */
81 assert (niov < NIOVMAX);
82 if ((iov[niov].iov_len = fmt - startp) != 0)
83 iov[niov++].iov_base = (char *) startp;
84
85 if (*fmt == '%')
86 {
87 /* It is a format specifier. */
88 char fill = ' ';
89 int width = -1;
90 int prec = -1;
91#if LONG_MAX != INT_MAX
92 int long_mod = 0;
93#endif
94
95 /* Recognize zero-digit fill flag. */
96 if (*++fmt == '0')
97 {
98 fill = '0';
99 ++fmt;
100 }
101
102 /* See whether with comes from a parameter. Note that no other
103 way to specify the width is implemented. */
104 if (*fmt == '*')
105 {
106 width = va_arg (arg, int);
107 /* The maximum padding accepted is up to pointer size. */
108 assert (width < IFMTSIZE);
109 ++fmt;
110 }
111
112 /* Handle precision. */
113 if (*fmt == '.' && fmt[1] == '*')
114 {
115 prec = va_arg (arg, int);
116 fmt += 2;
117 }
118
119 /* Recognize the l modifier. It is only important on some
120 platforms where long and int have a different size. We
121 can use the same code for size_t. */
122 if (*fmt == 'l' || *fmt == 'z')
123 {
124#if LONG_MAX != INT_MAX
125 long_mod = 1;
126#endif
127 ++fmt;
128 }
129
130 switch (*fmt)
131 {
132 /* Integer formatting. */
133 case 'd':
134 case 'u':
135 case 'x':
136 {
137 /* We have to make a difference if long and int have a
138 different size. */
139#if LONG_MAX != INT_MAX
140 unsigned long int num = (long_mod
141 ? va_arg (arg, unsigned long int)
142 : va_arg (arg, unsigned int));
143#else
144 unsigned long int num = va_arg (arg, unsigned int);
145#endif
146 bool negative = false;
147 if (*fmt == 'd')
148 {
149#if LONG_MAX != INT_MAX
150 if (long_mod)
151 {
152 if ((long int) num < 0)
153 negative = true;
154 }
155 else
156 {
157 if ((int) num < 0)
158 {
159 num = (unsigned int) num;
160 negative = true;
161 }
162 }
163#else
164 if ((int) num < 0)
165 negative = true;
166#endif
167 }
168
169 char *endp = &ifmtbuf[niov][IFMTSIZE];
170 char *cp = _itoa (num, endp, *fmt == 'x' ? 16 : 10, 0);
171
172 /* Pad to the width the user specified. */
173 if (width != -1)
174 while (endp - cp < width)
175 *--cp = fill;
176
177 if (negative)
178 *--cp = '-';
179
180 iov[niov].iov_base = cp;
181 iov[niov].iov_len = endp - cp;
182 ++niov;
183 }
184 break;
185
186 case 's':
187 /* Get the string argument. */
188 iov[niov].iov_base = va_arg (arg, char *);
189 iov[niov].iov_len = strlen (iov[niov].iov_base);
190 if (prec != -1)
191 iov[niov].iov_len = MIN ((size_t) prec, iov[niov].iov_len);
192 ++niov;
193 break;
194
195 case '%':
196 iov[niov].iov_base = (void *) fmt;
197 iov[niov].iov_len = 1;
198 ++niov;
199 break;
200
201 default:
202 assert (! "invalid format specifier");
203 }
204 ++fmt;
205 }
206 else if (*fmt == '\n')
207 {
208 /* See whether we have to print a single newline character. */
209 if (fmt == startp)
210 {
211 iov[niov].iov_base = (char *) startp;
212 iov[niov++].iov_len = 1;
213 }
214 else
215 /* No, just add it to the rest of the string. */
216 ++iov[niov - 1].iov_len;
217
218 /* Next line, print a tag again. */
219 tag_p = 1;
220 ++fmt;
221 }
222 }
223
224 /* Finally write the result. */
225 _dl_writev (fd, iov, niov);
226}
227
228
229/* Write to debug file. */
230void
231_dl_debug_printf (const char *fmt, ...)
232{
233 va_list arg;
234
235 va_start (arg, fmt);
236 _dl_debug_vdprintf (GLRO(dl_debug_fd), 1, fmt, arg);
237 va_end (arg);
238}
239
240
241/* Write to debug file but don't start with a tag. */
242void
243_dl_debug_printf_c (const char *fmt, ...)
244{
245 va_list arg;
246
247 va_start (arg, fmt);
248 _dl_debug_vdprintf (GLRO(dl_debug_fd), -1, fmt, arg);
249 va_end (arg);
250}
251
252
253/* Write the given file descriptor. */
254void
255_dl_dprintf (int fd, const char *fmt, ...)
256{
257 va_list arg;
258
259 va_start (arg, fmt);
260 _dl_debug_vdprintf (fd, 0, fmt, arg);
261 va_end (arg);
262}
263
264void
265_dl_printf (const char *fmt, ...)
266{
267 va_list arg;
268
269 va_start (arg, fmt);
270 _dl_debug_vdprintf (STDOUT_FILENO, 0, fmt, arg);
271 va_end (arg);
272}
273
274void
275_dl_error_printf (const char *fmt, ...)
276{
277 va_list arg;
278
279 va_start (arg, fmt);
280 _dl_debug_vdprintf (STDERR_FILENO, 0, fmt, arg);
281 va_end (arg);
282}
283
284void
285_dl_fatal_printf (const char *fmt, ...)
286{
287 va_list arg;
288
289 va_start (arg, fmt);
290 _dl_debug_vdprintf (STDERR_FILENO, 0, fmt, arg);
291 va_end (arg);
292 _exit (127);
293}
294rtld_hidden_def (_dl_fatal_printf)
295