[hackers] Re: [sbase][PATCH] ls and xargs: Reduce sbase-box static bss memory usage

From: Xan Phung <xan.phung_AT_gmail.com>
Date: Wed, 4 Jun 2025 15:01:31 +1000

Please ignore this email, I did a git sendmail with some final changes
which weren't committed yet.
I will resend this patch with the final changes committed.

On Wed, 4 Jun 2025 at 14:41, Xan Phung <xan.phung_AT_gmail.com> wrote:
>
> These two tools use large static buffers. In sbase-box, 146Kb is
> always allocated for them, even if they are not the tool being run.
>
> This patch changes their buffer allocation to use the stack instead
> of static memory. The bss size of sbase-box is reduced from 179Kb
> to 33Kb. Test scripts are provided for regression testing.
> ---
> ls.c | 6 +++--
> tests/ls-R.sh | 17 ++++++++++++++
> tests/ls-R.sh.expected | 48 +++++++++++++++++++++++++++++++++++++++
> tests/xargs-n.sh | 10 ++++++++
> tests/xargs-n.sh.expected | 5 ++++
> xargs.c | 10 ++++----
> 6 files changed, 89 insertions(+), 7 deletions(-)
> create mode 100755 tests/ls-R.sh
> create mode 100644 tests/ls-R.sh.expected
> create mode 100755 tests/xargs-n.sh
> create mode 100644 tests/xargs-n.sh.expected
>
> diff --git a/ls.c b/ls.c
> index aa95fef..869ecd1 100644
> --- a/ls.c
> +++ b/ls.c
> _AT_@ -30,10 +30,10 @@ struct entry {
> ino_t ino, tino;
> };
>
> -static struct {
> +static struct tree {
> dev_t dev;
> ino_t ino;
> -} tree[PATH_MAX];
> +} *tree;
>
> static int ret = 0;
> static int Aflag = 0;
> _AT_@ -369,7 +369,9 @@ int
> main(int argc, char *argv[])
> {
> struct entry ent, *dents, *fents;
> + struct tree treebuf[PATH_MAX] = {0};
> size_t i, ds, fs;
> + tree = treebuf;
>
> ARGBEGIN {
> case '1':
> diff --git a/tests/ls-R.sh b/tests/ls-R.sh
> new file mode 100755
> index 0000000..df70551
> --- /dev/null
> +++ b/tests/ls-R.sh
> _AT_@ -0,0 +1,17 @@
> +#!/bin/sh
> +TESTEXE="${TESTEXE:-../../ls}"
> +TESTARG="-R"
> +TESTINP=""
> +
> +mkdir -p ls-R.tmp || exit 2
> +cd ls-R.tmp || exit 2
> +mkdir -p test1 test2 test4 test5 test2/sub1 test2/sub2 || exit 2
> +touch testfile test2/sub1/file1 test2/sub1/file2 || exit 2
> +command -v "$TESTEXE" >/dev/null || exit 127
> +"$TESTEXE" $TESTARG >"../$0.out" 2>&1 test2 test3 test4 || fail=1
> +"$TESTEXE" $TESTARG >>"../$0.out" 2>&1 test4 test5 testfile || fail=1
> +"$TESTEXE" $TESTARG >>"../$0.out" 2>&1 . || fail=1
> +cd ..
> +cmp "$0.expected" "$0.out" || fail=1
> +exit $fail
> +
> diff --git a/tests/ls-R.sh.expected b/tests/ls-R.sh.expected
> new file mode 100644
> index 0000000..757eba2
> --- /dev/null
> +++ b/tests/ls-R.sh.expected
> _AT_@ -0,0 +1,48 @@
> +test2:
> +sub1
> +sub2
> +
> +test2/sub1:
> +file1
> +file2
> +
> +test2/sub2:
> +
> +test3:
> +sub1
> +sub2
> +
> +test3/sub1:
> +file1
> +file2
> +
> +test3/sub2:
> +
> +test4:
> +testfile
> +
> +test4:
> +
> +test5:
> +test1
> +test2
> +test3
> +test4
> +test5
> +testfile
> +
> +./test1:
> +
> +./test2:
> +sub1
> +sub2
> +
> +./test2/sub1:
> +file1
> +file2
> +
> +./test2/sub2:
> +
> +./test4:
> +
> +./test5:
> diff --git a/tests/xargs-n.sh b/tests/xargs-n.sh
> new file mode 100755
> index 0000000..a0c292c
> --- /dev/null
> +++ b/tests/xargs-n.sh
> _AT_@ -0,0 +1,10 @@
> +#!/bin/sh
> +TESTEXE="${TESTEXE:-../xargs}"
> +TESTARG="-n3"
> +TESTINP="aaaa bbb c\nddd eeee\nfffffff\nggggg h iiii\nj k l\na bbb"
> +
> +command -v "$TESTEXE" >/dev/null || exit 127
> +printf "$TESTINP" | "$TESTEXE" $TESTARG >"$0.out" 2>&1 || fail=1
> +cmp "$0.expected" "$0.out" || fail=1
> +exit $fail
> +
> diff --git a/tests/xargs-n.sh.expected b/tests/xargs-n.sh.expected
> new file mode 100644
> index 0000000..f2cc442
> --- /dev/null
> +++ b/tests/xargs-n.sh.expected
> _AT_@ -0,0 +1,5 @@
> +aaaa bbb c
> +ddd eeee fffffff
> +ggggg h iiii
> +j k l
> +a bbb
> diff --git a/xargs.c b/xargs.c
> index d9b2d98..cc48772 100644
> --- a/xargs.c
> +++ b/xargs.c
> _AT_@ -20,7 +20,7 @@ static int parsequote(int);
> static int parseescape(void);
> static char *poparg(void);
> static void waitchld(void);
> -static void spawn(void);
> +static void spawn(char **);
>
> static size_t argbsz;
> static size_t argbpos;
> _AT_@ -28,7 +28,6 @@ static size_t maxargs = 0;
> static int nerrors = 0;
> static int rflag = 0, nflag = 0, tflag = 0, xflag = 0, Iflag = 0;
> static char *argb;
> -static char *cmd[NARGS];
> static char *eofstr;
>
> static int
> _AT_@ -162,7 +161,7 @@ waitchld(void)
> }
>
> static void
> -spawn(void)
> +spawn(char *cmd[])
> {
> int savederrno;
> int first = 1;
> _AT_@ -203,6 +202,7 @@ main(int argc, char *argv[])
> int ret = 0, leftover = 0, i, j;
> size_t argsz, argmaxsz;
> size_t arglen, a;
> + char *cmd[NARGS];
> char *arg = "";
> char *replstr;
>
> _AT_@ -287,11 +287,11 @@ main(int argc, char *argv[])
> }
> cmd[i] = NULL;
> if (a >= maxargs && nflag)
> - spawn();
> + spawn(cmd);
> else if (!a || (i == 1 && rflag))
> ;
> else
> - spawn();
> + spawn(cmd);
> for (; i >= 0; i--)
> free(cmd[i]);
> } while (arg);
> --
> 2.49.0
>
Received on Wed Jun 04 2025 - 07:01:31 CEST