freebsd-src/usr.bin/hexdump/display.c
Ricardo Branco e23954bd42 hexdump: Do not trust st_size if it equals zero.
Fix for hexdump -s not being able to skip files residing in
pseudo-filesystems that advertise a zero size value.

Historically, many pseudofs-based filesystems (e.g., procfs) report
a va_size of 0 for numerous files classified as regular files.
Typically, the contents of these files are generated on demand
from kernel data as sbuf(9) strings at the time they are read.
Accurately reporting the size of these files is challenging, as it
often involves generating their contents. These pseudofs implementations
frequently report the size as 0. This is a historical behavior and also
aligns with Linux behavior. To maintain compatibility, we have chosen
to preserve the existing behavior and address it in the userland
application, rather than modifying it in the kernel (by updating the
correct value for va_size).

PR:		bin/276106
MFC after:	1 week
2024-01-04 00:16:50 -08:00

435 lines
9.3 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/conf.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <capsicum_helpers.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "hexdump.h"
enum _vflag vflag = FIRST;
static off_t address; /* address/offset in stream */
static off_t eaddress; /* end address */
static void print(PR *, u_char *);
static void noseek(void);
void
display(void)
{
FS *fs;
FU *fu;
PR *pr;
int cnt;
u_char *bp;
off_t saveaddress;
u_char savech, *savebp;
savech = 0;
while ((bp = get()))
for (fs = fshead, savebp = bp, saveaddress = address; fs;
fs = fs->nextfs, bp = savebp, address = saveaddress)
for (fu = fs->nextfu; fu; fu = fu->nextfu) {
if (fu->flags&F_IGNORE)
break;
for (cnt = fu->reps; cnt; --cnt)
for (pr = fu->nextpr; pr; address += pr->bcnt,
bp += pr->bcnt, pr = pr->nextpr) {
if (eaddress && address >= eaddress &&
!(pr->flags & (F_TEXT|F_BPAD)))
bpad(pr);
if (cnt == 1 && pr->nospace) {
savech = *pr->nospace;
*pr->nospace = '\0';
}
print(pr, bp);
if (cnt == 1 && pr->nospace)
*pr->nospace = savech;
}
}
if (endfu) {
/*
* If eaddress not set, error or file size was multiple of
* blocksize, and no partial block ever found.
*/
if (!eaddress) {
if (!address)
return;
eaddress = address;
}
for (pr = endfu->nextpr; pr; pr = pr->nextpr)
switch(pr->flags) {
case F_ADDRESS:
(void)printf(pr->fmt, (quad_t)eaddress);
break;
case F_TEXT:
(void)printf("%s", pr->fmt);
break;
}
}
}
static void
print(PR *pr, u_char *bp)
{
long double ldbl;
double f8;
float f4;
int16_t s2;
int32_t s4;
int64_t s8;
u_int16_t u2;
u_int32_t u4;
u_int64_t u8;
switch(pr->flags) {
case F_ADDRESS:
(void)printf(pr->fmt, (quad_t)address);
break;
case F_BPAD:
(void)printf(pr->fmt, "");
break;
case F_C:
conv_c(pr, bp, eaddress ? eaddress - address :
blocksize - address % blocksize);
break;
case F_CHAR:
(void)printf(pr->fmt, *bp);
break;
case F_DBL:
switch(pr->bcnt) {
case 4:
bcopy(bp, &f4, sizeof(f4));
(void)printf(pr->fmt, f4);
break;
case 8:
bcopy(bp, &f8, sizeof(f8));
(void)printf(pr->fmt, f8);
break;
default:
if (pr->bcnt == sizeof(long double)) {
bcopy(bp, &ldbl, sizeof(ldbl));
(void)printf(pr->fmt, ldbl);
}
break;
}
break;
case F_INT:
switch(pr->bcnt) {
case 1:
(void)printf(pr->fmt, (quad_t)(signed char)*bp);
break;
case 2:
bcopy(bp, &s2, sizeof(s2));
(void)printf(pr->fmt, (quad_t)s2);
break;
case 4:
bcopy(bp, &s4, sizeof(s4));
(void)printf(pr->fmt, (quad_t)s4);
break;
case 8:
bcopy(bp, &s8, sizeof(s8));
(void)printf(pr->fmt, s8);
break;
}
break;
case F_P:
(void)printf(pr->fmt, isprint(*bp) ? *bp : '.');
break;
case F_STR:
(void)printf(pr->fmt, (char *)bp);
break;
case F_TEXT:
(void)printf("%s", pr->fmt);
break;
case F_U:
conv_u(pr, bp);
break;
case F_UINT:
switch(pr->bcnt) {
case 1:
(void)printf(pr->fmt, (u_quad_t)*bp);
break;
case 2:
bcopy(bp, &u2, sizeof(u2));
(void)printf(pr->fmt, (u_quad_t)u2);
break;
case 4:
bcopy(bp, &u4, sizeof(u4));
(void)printf(pr->fmt, (u_quad_t)u4);
break;
case 8:
bcopy(bp, &u8, sizeof(u8));
(void)printf(pr->fmt, u8);
break;
}
break;
}
}
void
bpad(PR *pr)
{
static char const *spec = " -0+#";
char *p1, *p2;
/*
* Remove all conversion flags; '-' is the only one valid
* with %s, and it's not useful here.
*/
pr->flags = F_BPAD;
pr->cchar[0] = 's';
pr->cchar[1] = '\0';
for (p1 = pr->fmt; *p1 != '%'; ++p1);
for (p2 = ++p1; *p1 && strchr(spec, *p1); ++p1);
while ((*p2++ = *p1++));
}
static char **_argv;
u_char *
get(void)
{
static int ateof = 1;
static u_char *curp, *savp;
int n;
int need, nread;
int valid_save = 0;
u_char *tmpp;
if (!curp) {
if ((curp = calloc(1, blocksize)) == NULL)
err(1, NULL);
if ((savp = calloc(1, blocksize)) == NULL)
err(1, NULL);
} else {
tmpp = curp;
curp = savp;
savp = tmpp;
address += blocksize;
valid_save = 1;
}
for (need = blocksize, nread = 0;;) {
/*
* if read the right number of bytes, or at EOF for one file,
* and no other files are available, zero-pad the rest of the
* block and set the end flag.
*/
if (!length || (ateof && !next((char **)NULL))) {
if (odmode && skip > 0)
errx(1, "cannot skip past end of input");
if (need == blocksize)
return((u_char *)NULL);
/*
* XXX bcmp() is not quite right in the presence
* of multibyte characters.
*/
if (need == 0 && vflag != ALL &&
valid_save &&
bcmp(curp, savp, nread) == 0) {
if (vflag != DUP) {
(void)printf("*\n");
(void)fflush(stdout);
}
return((u_char *)NULL);
}
bzero((char *)curp + nread, need);
eaddress = address + nread;
return(curp);
}
n = fread((char *)curp + nread, sizeof(u_char),
length == -1 ? need : MIN(length, need), stdin);
if (!n) {
if (ferror(stdin))
warn("%s", _argv[-1]);
ateof = 1;
continue;
}
ateof = 0;
if (length != -1)
length -= n;
if (!(need -= n)) {
/*
* XXX bcmp() is not quite right in the presence
* of multibyte characters.
*/
if (vflag == ALL || vflag == FIRST ||
valid_save == 0 ||
bcmp(curp, savp, blocksize) != 0) {
if (vflag == DUP || vflag == FIRST)
vflag = WAIT;
return(curp);
}
if (vflag == WAIT) {
(void)printf("*\n");
(void)fflush(stdout);
}
vflag = DUP;
address += blocksize;
need = blocksize;
nread = 0;
}
else
nread += n;
}
}
size_t
peek(u_char *buf, size_t nbytes)
{
size_t n, nread;
int c;
if (length != -1 && nbytes > (unsigned int)length)
nbytes = length;
nread = 0;
while (nread < nbytes && (c = getchar()) != EOF) {
*buf++ = c;
nread++;
}
n = nread;
while (n-- > 0) {
c = *--buf;
ungetc(c, stdin);
}
return (nread);
}
int
next(char **argv)
{
static int done;
int statok;
if (argv) {
_argv = argv;
return(1);
}
for (;;) {
if (*_argv) {
done = 1;
if (!(freopen(*_argv, "r", stdin))) {
warn("%s", *_argv);
exitval = 1;
++_argv;
continue;
}
statok = 1;
} else {
if (done++)
return(0);
statok = 0;
}
if (caph_limit_stream(fileno(stdin), CAPH_READ) < 0)
err(1, "unable to restrict %s",
statok ? *_argv : "stdin");
/*
* We've opened our last input file; enter capsicum sandbox.
*/
if (statok == 0 || *(_argv + 1) == NULL) {
if (caph_enter() < 0)
err(1, "unable to enter capability mode");
}
if (skip)
doskip(statok ? *_argv : "stdin", statok);
if (*_argv)
++_argv;
if (!skip)
return(1);
}
/* NOTREACHED */
}
void
doskip(const char *fname, int statok)
{
int type;
struct stat sb;
if (statok) {
if (fstat(fileno(stdin), &sb))
err(1, "%s", fname);
if (S_ISREG(sb.st_mode) && skip > sb.st_size && sb.st_size > 0) {
address += sb.st_size;
skip -= sb.st_size;
return;
}
}
if (!statok || S_ISFIFO(sb.st_mode) || S_ISSOCK(sb.st_mode) || \
(S_ISREG(sb.st_mode) && sb.st_size == 0)) {
noseek();
return;
}
if (S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode)) {
if (ioctl(fileno(stdin), FIODTYPE, &type))
err(1, "%s", fname);
/*
* Most tape drives don't support seeking,
* yet fseek() would succeed.
*/
if (type & D_TAPE) {
noseek();
return;
}
}
if (fseeko(stdin, skip, SEEK_SET)) {
noseek();
return;
}
address += skip;
skip = 0;
}
static void
noseek(void)
{
int count;
for (count = 0; count < skip; ++count)
if (getchar() == EOF)
break;
address += count;
skip -= count;
}