busybox/shell/shell_common.c
Eicke Herbertz 1b30c63dfd shell: also do word splitting when -d DELIM is used
The original commit 3bef5d89b0 introduced an additional check
for an unset `opt_d` before doing word splitting. I'm unsure
why it's there in the first place, but the commit message also
describes a different behaviour than what -d actually does in
bash, while the code mostly does the right thing.

`opt_d` sets the line delimiter for read to stop reading and
should not affect word splitting.

Testcase:
$ echo qwe rty | { read -d Z a b; echo a:$a b:$b; }
a:qwe b:rty

function                                             old     new   delta
shell_builtin_read                                  1314    1304     -10

Signed-off-by: Eicke Herbertz <wolletd@posteo.de>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2021-06-05 18:06:47 +02:00

690 lines
16 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Adapted from ash applet code
*
* This code is derived from software contributed to Berkeley by
* Kenneth Almquist.
*
* Copyright (c) 1989, 1991, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
* was re-ported from NetBSD and debianized.
*
* Copyright (c) 2010 Denys Vlasenko
* Split from ash.c
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
#include "shell_common.h"
const char defifsvar[] ALIGN1 = "IFS= \t\n";
const char defoptindvar[] ALIGN1 = "OPTIND=1";
/* read builtin */
/* Needs to be interruptible: shell must handle traps and shell-special signals
* while inside read. To implement this, be sure to not loop on EINTR
* and return errno == EINTR reliably.
*/
//TODO: use more efficient setvar() which takes a pointer to malloced "VAR=VAL"
//string. hush naturally has it, and ash has setvareq().
//Here we can simply store "VAR=" at buffer start and store read data directly
//after "=", then pass buffer to setvar() to consume.
const char* FAST_FUNC
shell_builtin_read(struct builtin_read_params *params)
{
struct pollfd pfd[1];
#define fd (pfd[0].fd) /* -u FD */
unsigned err;
unsigned end_ms; /* -t TIMEOUT */
int nchars; /* -n NUM */
char **pp;
char *buffer;
char delim;
struct termios tty, old_tty;
const char *retval;
int bufpos; /* need to be able to hold -1 */
int startword;
smallint backslash;
char **argv;
const char *ifs;
int read_flags;
errno = err = 0;
argv = params->argv;
pp = argv;
while (*pp) {
if (endofname(*pp)[0] != '\0') {
/* Mimic bash message */
bb_error_msg("read: '%s': not a valid identifier", *pp);
return (const char *)(uintptr_t)1;
}
pp++;
}
nchars = 0; /* if != 0, -n is in effect */
if (params->opt_n) {
nchars = bb_strtou(params->opt_n, NULL, 10);
if (nchars < 0 || errno)
return "invalid count";
/* note: "-n 0": off (bash 3.2 does this too) */
}
end_ms = 0;
if (params->opt_t && !ENABLE_FEATURE_SH_READ_FRAC) {
end_ms = bb_strtou(params->opt_t, NULL, 10);
if (errno)
return "invalid timeout";
if (end_ms > UINT_MAX / 2048) /* be safely away from overflow */
end_ms = UINT_MAX / 2048;
end_ms *= 1000;
}
if (params->opt_t && ENABLE_FEATURE_SH_READ_FRAC) {
/* bash 4.3 (maybe earlier) supports -t N.NNNNNN */
char *p;
/* Eat up to three fractional digits */
int frac_digits = 3 + 1;
end_ms = bb_strtou(params->opt_t, &p, 10);
if (end_ms > UINT_MAX / 2048) /* be safely away from overflow */
end_ms = UINT_MAX / 2048;
if (errno) {
/* EINVAL = number is ok, but not NUL terminated */
if (errno != EINVAL || *p != '.')
return "invalid timeout";
/* Do not check the rest: bash allows "0.123456xyz" */
while (*++p && --frac_digits) {
end_ms *= 10;
end_ms += (*p - '0');
if ((unsigned char)(*p - '0') > 9)
return "invalid timeout";
}
}
while (--frac_digits > 0) {
end_ms *= 10;
}
}
fd = STDIN_FILENO;
if (params->opt_u) {
fd = bb_strtou(params->opt_u, NULL, 10);
if (fd < 0 || errno)
return "invalid file descriptor";
}
if (params->opt_t && end_ms == 0) {
/* "If timeout is 0, read returns immediately, without trying
* to read any data. The exit status is 0 if input is available
* on the specified file descriptor, non-zero otherwise."
* bash seems to ignore -p PROMPT for this use case.
*/
int r;
pfd[0].events = POLLIN;
r = poll(pfd, 1, /*timeout:*/ 0);
/* Return 0 only if poll returns 1 ("one fd ready"), else return 1: */
return (const char *)(uintptr_t)(r <= 0);
}
if (params->opt_p && isatty(fd)) {
fputs(params->opt_p, stderr);
fflush_all();
}
ifs = params->ifs;
if (ifs == NULL)
ifs = defifs;
read_flags = params->read_flags;
if (nchars || (read_flags & BUILTIN_READ_SILENT)) {
tcgetattr(fd, &tty);
old_tty = tty;
if (nchars) {
tty.c_lflag &= ~ICANON;
// Setting it to more than 1 breaks poll():
// it blocks even if there's data. !??
//tty.c_cc[VMIN] = nchars < 256 ? nchars : 255;
/* reads will block only if < 1 char is available */
tty.c_cc[VMIN] = 1;
/* no timeout (reads block forever) */
tty.c_cc[VTIME] = 0;
}
if (read_flags & BUILTIN_READ_SILENT) {
tty.c_lflag &= ~(ECHO | ECHOK | ECHONL);
}
/* This forces execution of "restoring" tcgetattr later */
read_flags |= BUILTIN_READ_SILENT;
/* if tcgetattr failed, tcsetattr will fail too.
* Ignoring, it's harmless. */
tcsetattr(fd, TCSANOW, &tty);
}
retval = (const char *)(uintptr_t)0;
startword = 1;
backslash = 0;
if (params->opt_t)
end_ms += (unsigned)monotonic_ms();
buffer = NULL;
bufpos = 0;
delim = params->opt_d ? params->opt_d[0] : '\n';
do {
char c;
int timeout;
if ((bufpos & 0xff) == 0)
buffer = xrealloc(buffer, bufpos + 0x101);
timeout = -1;
if (params->opt_t) {
timeout = end_ms - (unsigned)monotonic_ms();
/* ^^^^^^^^^^^^^ all values are unsigned,
* wrapping math is used here, good even if
* 32-bit unix time wrapped (year 2038+).
*/
if (timeout <= 0) { /* already late? */
retval = (const char *)(uintptr_t)1;
goto ret;
}
}
/* We must poll even if timeout is -1:
* we want to be interrupted if signal arrives,
* regardless of SA_RESTART-ness of that signal!
*/
errno = 0;
pfd[0].events = POLLIN;
if (poll(pfd, 1, timeout) <= 0) {
/* timed out, or EINTR */
err = errno;
retval = (const char *)(uintptr_t)1;
goto ret;
}
if (read(fd, &buffer[bufpos], 1) != 1) {
err = errno;
retval = (const char *)(uintptr_t)1;
break;
}
c = buffer[bufpos];
if (!(read_flags & BUILTIN_READ_RAW)) {
if (backslash) {
backslash = 0;
if (c != '\n')
goto put;
continue;
}
if (c == '\\') {
backslash = 1;
continue;
}
}
if (c == delim) /* '\n' or -d CHAR */
break;
if (c == '\0')
continue;
/* $IFS splitting. NOT done if we run "read"
* without variable names (bash compat).
* Thus, "read" and "read REPLY" are not the same.
*/
if (argv[0]) {
/* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05 */
const char *is_ifs = strchr(ifs, c);
if (startword && is_ifs) {
if (isspace(c))
continue;
/* it is a non-space ifs char */
startword--;
if (startword == 1) /* first one? */
continue; /* yes, it is not next word yet */
}
startword = 0;
if (argv[1] != NULL && is_ifs) {
buffer[bufpos] = '\0';
bufpos = 0;
params->setvar(*argv, buffer);
argv++;
/* can we skip one non-space ifs char? (2: yes) */
startword = isspace(c) ? 2 : 1;
continue;
}
}
put:
bufpos++;
} while (--nchars);
if (argv[0]) {
/* Remove trailing space $IFS chars */
while (--bufpos >= 0
&& isspace(buffer[bufpos])
&& strchr(ifs, buffer[bufpos]) != NULL
) {
continue;
}
buffer[bufpos + 1] = '\0';
/* Last variable takes the entire remainder with delimiters
* (sans trailing whitespace $IFS),
* but ***only "if there are fewer vars than fields"(c)***!
* The "X:Y:" case below: there are two fields,
* and therefore last delimiter (:) is eaten:
* IFS=": "
* echo "X:Y:Z:" | (read x y; echo "|$x|$y|") # |X|Y:Z:|
* echo "X:Y:Z" | (read x y; echo "|$x|$y|") # |X|Y:Z|
* echo "X:Y:" | (read x y; echo "|$x|$y|") # |X|Y|, not |X|Y:|
* echo "X:Y : " | (read x y; echo "|$x|$y|") # |X|Y|
*/
if (bufpos >= 0
&& strchr(ifs, buffer[bufpos]) != NULL
) {
/* There _is_ a non-whitespace IFS char */
/* Skip whitespace IFS char before it */
while (--bufpos >= 0
&& isspace(buffer[bufpos])
&& strchr(ifs, buffer[bufpos]) != NULL
) {
continue;
}
/* Are there $IFS chars? */
if (strcspn(buffer, ifs) >= ++bufpos) {
/* No: last var takes one field, not more */
/* So, drop trailing IFS delims */
buffer[bufpos] = '\0';
}
}
/* Use the remainder as a value for the next variable */
params->setvar(*argv, buffer);
/* Set the rest to "" */
while (*++argv)
params->setvar(*argv, "");
} else {
/* Note: no $IFS removal */
buffer[bufpos] = '\0';
params->setvar("REPLY", buffer);
}
ret:
free(buffer);
if (read_flags & BUILTIN_READ_SILENT)
tcsetattr(fd, TCSANOW, &old_tty);
errno = err;
return retval;
#undef fd
}
/* ulimit builtin */
struct limits {
uint8_t cmd; /* RLIMIT_xxx fit into it */
uint8_t factor_shift; /* shift by to get rlim_{cur,max} values */
};
/* Order of entries matches order in which bash prints "ulimit -a" */
static const struct limits limits_tbl[] ALIGN2 = {
{ RLIMIT_CORE, 9, }, // -c
{ RLIMIT_DATA, 10, }, // -d
#ifdef RLIMIT_NICE
{ RLIMIT_NICE, 0, }, // -e
#define LIMIT_F_IDX 3
#else
/* for example, Hurd */
#define LIMIT_F_IDX 2
#endif
{ RLIMIT_FSIZE, 9, }, // -f
#ifdef RLIMIT_SIGPENDING
{ RLIMIT_SIGPENDING, 0, }, // -i
#endif
#ifdef RLIMIT_MEMLOCK
{ RLIMIT_MEMLOCK, 10, }, // -l
#endif
#ifdef RLIMIT_RSS
{ RLIMIT_RSS, 10, }, // -m
#endif
#ifdef RLIMIT_NOFILE
{ RLIMIT_NOFILE, 0, }, // -n
#endif
#ifdef RLIMIT_MSGQUEUE
{ RLIMIT_MSGQUEUE, 0, }, // -q
#endif
#ifdef RLIMIT_RTPRIO
{ RLIMIT_RTPRIO, 0, }, // -r
#endif
#ifdef RLIMIT_STACK
{ RLIMIT_STACK, 10, }, // -s
#endif
#ifdef RLIMIT_CPU
{ RLIMIT_CPU, 0, }, // -t
#endif
#ifdef RLIMIT_NPROC
{ RLIMIT_NPROC, 0, }, // -u
#endif
#ifdef RLIMIT_AS
{ RLIMIT_AS, 10, }, // -v
#endif
#ifdef RLIMIT_LOCKS
{ RLIMIT_LOCKS, 0, }, // -x
#endif
};
// 1) bash also shows:
//pipe size (512 bytes, -p) 8
// 2) RLIMIT_RTTIME ("timeout for RT tasks in us") is not in the table
static const char limits_help[] ALIGN1 =
"core file size (blocks)" // -c
"\0""data seg size (kb)" // -d
#ifdef RLIMIT_NICE
"\0""scheduling priority" // -e
#endif
"\0""file size (blocks)" // -f
#ifdef RLIMIT_SIGPENDING
"\0""pending signals" // -i
#endif
#ifdef RLIMIT_MEMLOCK
"\0""max locked memory (kb)" // -l
#endif
#ifdef RLIMIT_RSS
"\0""max memory size (kb)" // -m
#endif
#ifdef RLIMIT_NOFILE
"\0""open files" // -n
#endif
#ifdef RLIMIT_MSGQUEUE
"\0""POSIX message queues (bytes)" // -q
#endif
#ifdef RLIMIT_RTPRIO
"\0""real-time priority" // -r
#endif
#ifdef RLIMIT_STACK
"\0""stack size (kb)" // -s
#endif
#ifdef RLIMIT_CPU
"\0""cpu time (seconds)" // -t
#endif
#ifdef RLIMIT_NPROC
"\0""max user processes" // -u
#endif
#ifdef RLIMIT_AS
"\0""virtual memory (kb)" // -v
#endif
#ifdef RLIMIT_LOCKS
"\0""file locks" // -x
#endif
;
static const char limit_chars[] ALIGN1 =
"c"
"d"
#ifdef RLIMIT_NICE
"e"
#endif
"f"
#ifdef RLIMIT_SIGPENDING
"i"
#endif
#ifdef RLIMIT_MEMLOCK
"l"
#endif
#ifdef RLIMIT_RSS
"m"
#endif
#ifdef RLIMIT_NOFILE
"n"
#endif
#ifdef RLIMIT_MSGQUEUE
"q"
#endif
#ifdef RLIMIT_RTPRIO
"r"
#endif
#ifdef RLIMIT_STACK
"s"
#endif
#ifdef RLIMIT_CPU
"t"
#endif
#ifdef RLIMIT_NPROC
"u"
#endif
#ifdef RLIMIT_AS
"v"
#endif
#ifdef RLIMIT_LOCKS
"x"
#endif
;
/* "-": treat args as parameters of option with ASCII code 1 */
static const char ulimit_opt_string[] ALIGN1 = "-HSa"
"c::"
"d::"
#ifdef RLIMIT_NICE
"e::"
#endif
"f::"
#ifdef RLIMIT_SIGPENDING
"i::"
#endif
#ifdef RLIMIT_MEMLOCK
"l::"
#endif
#ifdef RLIMIT_RSS
"m::"
#endif
#ifdef RLIMIT_NOFILE
"n::"
#endif
#ifdef RLIMIT_MSGQUEUE
"q::"
#endif
#ifdef RLIMIT_RTPRIO
"r::"
#endif
#ifdef RLIMIT_STACK
"s::"
#endif
#ifdef RLIMIT_CPU
"t::"
#endif
#ifdef RLIMIT_NPROC
"u::"
#endif
#ifdef RLIMIT_AS
"v::"
#endif
#ifdef RLIMIT_LOCKS
"x::"
#endif
;
enum {
OPT_hard = (1 << 0),
OPT_soft = (1 << 1),
OPT_all = (1 << 2),
};
static void printlim(unsigned opts, const struct rlimit *limit,
const struct limits *l)
{
rlim_t val;
val = limit->rlim_max;
if (opts & OPT_soft)
val = limit->rlim_cur;
if (val == RLIM_INFINITY)
puts("unlimited");
else {
val >>= l->factor_shift;
printf("%llu\n", (long long) val);
}
}
int FAST_FUNC
shell_builtin_ulimit(char **argv)
{
struct rlimit limit;
unsigned opt_cnt;
unsigned opts;
unsigned argc;
unsigned i;
/* We can't use getopt32: need to handle commands like
* ulimit 123 -c2 -l 456
*/
/* In case getopt() was already called:
* reset libc getopt() internal state.
*/
GETOPT_RESET();
// bash 4.4.23:
//
// -H and/or -S change meaning even of options *before* them: ulimit -f 2000 -H
// sets hard limit, ulimit -a -H prints hard limits.
//
// -a is equivalent for requesting all limits to be shown.
//
// If -a is specified, attempts to set limits are ignored:
// ulimit -m 1000; ulimit -m 2000 -a
// shows 1000, not 2000. HOWEVER, *implicit* -f form "ulimit 2000 -a"
// DOES set -f limit [we don't implement this quirk], "ulimit -a 2000" does not.
// Options are still parsed: ulimit -az complains about unknown -z opt.
//
// -a is not cumulative: "ulimit -a -a" = "ulimit -a -f -m" = "ulimit -a"
//
// -HSa can be combined in one argument and with one other option (example: -Sm),
// but other options can't: limit value is an optional argument,
// thus "-mf" means "-m f", f is the parameter of -m.
//
// Limit can be set and then printed: ulimit -m 2000 -m
// If set more than once, they are set and printed in order:
// try ulimit -m -m 1000 -m -m 2000 -m -m 3000 -m
//
// Limits are shown in the order of options given:
// ulimit -m -f is not the same as ulimit -f -m.
//
// If both -S and -H are given, show soft limit.
//
// Short printout (limit value only) is printed only if just one option
// is given: ulimit -m. ulimit -f -m prints verbose lines.
// ulimit -f -f prints same verbose line twice.
// ulimit -m 10000 -f prints verbose line for -f.
argc = string_array_len(argv);
/* First pass over options: detect -H/-S/-a status,
* and "bare ulimit" and "only one option" cases
* by counting other opts.
*/
opt_cnt = 0;
opts = 0;
while (1) {
int opt_char = getopt(argc, argv, ulimit_opt_string);
if (opt_char == -1)
break;
if (opt_char == 'H') {
opts |= OPT_hard;
continue;
}
if (opt_char == 'S') {
opts |= OPT_soft;
continue;
}
if (opt_char == 'a') {
opts |= OPT_all;
continue;
}
if (opt_char == '?') {
/* bad option. getopt already complained. */
return EXIT_FAILURE;
}
opt_cnt++;
} /* while (there are options) */
if (!(opts & (OPT_hard | OPT_soft)))
opts |= (OPT_hard | OPT_soft);
if (opts & OPT_all) {
const char *help = limits_help;
for (i = 0; i < ARRAY_SIZE(limits_tbl); i++) {
getrlimit(limits_tbl[i].cmd, &limit);
printf("%-32s(-%c) ", help, limit_chars[i]);
printlim(opts, &limit, &limits_tbl[i]);
help += strlen(help) + 1;
}
return EXIT_SUCCESS;
}
/* Second pass: set or print limits, in order */
GETOPT_RESET();
while (1) {
char *val_str;
int opt_char = getopt(argc, argv, ulimit_opt_string);
if (opt_char == -1)
break;
if (opt_char == 'H')
continue;
if (opt_char == 'S')
continue;
//if (opt_char == 'a') - impossible
if (opt_char == 1) /* if "ulimit NNN", -f is assumed */
opt_char = 'f';
i = strchrnul(limit_chars, opt_char) - limit_chars;
//if (i >= ARRAY_SIZE(limits_tbl)) - bad option, impossible
val_str = optarg;
if (!val_str && argv[optind] && argv[optind][0] != '-')
val_str = argv[optind++]; /* ++ skips NN in "-c NN" case */
getrlimit(limits_tbl[i].cmd, &limit);
if (!val_str) {
if (opt_cnt > 1)
printf("%-32s(-%c) ", nth_string(limits_help, i), limit_chars[i]);
printlim(opts, &limit, &limits_tbl[i]);
} else {
rlim_t val = RLIM_INFINITY;
if (strcmp(val_str, "unlimited") != 0) {
if (sizeof(val) == sizeof(int))
val = bb_strtou(val_str, NULL, 10);
else if (sizeof(val) == sizeof(long))
val = bb_strtoul(val_str, NULL, 10);
else
val = bb_strtoull(val_str, NULL, 10);
if (errno) {
bb_error_msg("invalid number '%s'", val_str);
return EXIT_FAILURE;
}
val <<= limits_tbl[i].factor_shift;
}
//bb_error_msg("opt %c val_str:'%s' val:%lld", opt_char, val_str, (long long)val);
/* from man bash: "If neither -H nor -S
* is specified, both the soft and hard
* limits are set. */
if (opts & OPT_hard)
limit.rlim_max = val;
if (opts & OPT_soft)
limit.rlim_cur = val;
//bb_error_msg("setrlimit(%d, %lld, %lld)", limits_tbl[i].cmd, (long long)limit.rlim_cur, (long long)limit.rlim_max);
if (setrlimit(limits_tbl[i].cmd, &limit) < 0) {
bb_simple_perror_msg("error setting limit");
return EXIT_FAILURE;
}
}
} /* while (there are options) */
if (opt_cnt == 0) {
/* "bare ulimit": treat it as if it was -f */
getrlimit(RLIMIT_FSIZE, &limit);
printlim(opts, &limit, &limits_tbl[LIMIT_F_IDX]);
}
return EXIT_SUCCESS;
}