sbase/du.c

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2.1 KiB
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/* See LICENSE file for copyright and license details. */
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#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>
#include <limits.h>
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#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
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#include <unistd.h>
#include "fs.h"
#include "util.h"
static size_t maxdepth = SIZE_MAX;
static size_t blksize = 512;
static int aflag = 0;
static int sflag = 0;
static int hflag = 0;
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static void
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printpath(off_t n, const char *path)
{
if (hflag)
printf("%s\t%s\n", humansize(n * blksize), path);
else
printf("%jd\t%s\n", (intmax_t)n, path);
}
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static off_t
nblks(blkcnt_t blocks)
{
return (512 * blocks + blksize - 1) / blksize;
}
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static void
du(const char *path, struct stat *st, void *data, struct recursor *r)
{
off_t *total = data, subtotal;
subtotal = nblks(st->st_blocks);
if (S_ISDIR(st->st_mode))
recurse(path, &subtotal, r);
*total += subtotal;
if (!r->depth)
printpath(*total, path);
else if (!sflag && r->depth <= maxdepth && (S_ISDIR(st->st_mode) || aflag))
printpath(subtotal, path);
}
static void
usage(void)
{
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eprintf("usage: %s [-a | -s] [-d depth] [-h] [-k] [-H | -L | -P] [-x] [file ...]\n", argv0);
}
int
main(int argc, char *argv[])
{
struct recursor r = { .fn = du, .hist = NULL, .depth = 0, .maxdepth = 0,
.follow = 'P', .flags = 0 };
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off_t n = 0;
int kflag = 0, dflag = 0;
char *bsize;
ARGBEGIN {
case 'a':
aflag = 1;
break;
case 'd':
dflag = 1;
maxdepth = estrtonum(EARGF(usage()), 0, MIN(LLONG_MAX, SIZE_MAX));
break;
case 'h':
hflag = 1;
break;
case 'k':
kflag = 1;
break;
case 's':
sflag = 1;
break;
case 'x':
r.flags |= SAMEDEV;
break;
case 'H':
case 'L':
case 'P':
r.follow = ARGC();
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break;
default:
usage();
} ARGEND
if ((aflag && sflag) || (dflag && sflag))
usage();
bsize = getenv("BLOCKSIZE");
if (bsize)
blksize = estrtonum(bsize, 1, MIN(LLONG_MAX, SIZE_MAX));
if (kflag)
blksize = 1024;
if (!argc) {
Refactor recurse() again Okay, why yet another recurse()-refactor? The last one added the recursor-struct, which simplified things on the user-end, but there was still one thing that bugged me a lot: Previously, all fn()'s were forced to (l)stat the paths themselves. This does not work well when you try to keep up with H-, L- and P- flags at the same time, as each utility-function would have to set the right function-pointer for (l)stat every single time. This is not desirable. Furthermore, recurse should be easy to use and not involve trouble finding the right (l)stat-function to do it right. So, what we needed was a stat-argument for each fn(), so it is directly accessible. This was impossible to do though when the fn()'s are still directly called by the programs to "start" the recurse. Thus, the fundamental change is to make recurse() the function to go, while designing the fn()'s in a way they can "live" with st being NULL (we don't want a null-pointer-deref). What you can see in this commit is the result of this work. Why all this trouble instead of using nftw? The special thing about recurse() is that you tell the function when to recurse() in your fn(). You don't need special flags to tell nftw() to skip the subtree, just to give an example. The only single downside to this is that now, you are not allowed to unconditionally call recurse() from your fn(). It has to be a directory. However, that is a cost I think is easily weighed up by the advantages. Another thing is the history: I added a procedure at the end of the outmost recurse to free the history. This way we don't leak memory. A simple optimization on the side: - if (h->dev == st.st_dev && h->ino == st.st_ino) + if (h->ino == st.st_ino && h->dev == st.st_dev) First compare the likely difference in inode-numbers instead of checking the unlikely condition that the device-numbers are different.
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recurse(".", &n, &r);
} else {
for (; *argv; argc--, argv++) {
n = 0;
Refactor recurse() again Okay, why yet another recurse()-refactor? The last one added the recursor-struct, which simplified things on the user-end, but there was still one thing that bugged me a lot: Previously, all fn()'s were forced to (l)stat the paths themselves. This does not work well when you try to keep up with H-, L- and P- flags at the same time, as each utility-function would have to set the right function-pointer for (l)stat every single time. This is not desirable. Furthermore, recurse should be easy to use and not involve trouble finding the right (l)stat-function to do it right. So, what we needed was a stat-argument for each fn(), so it is directly accessible. This was impossible to do though when the fn()'s are still directly called by the programs to "start" the recurse. Thus, the fundamental change is to make recurse() the function to go, while designing the fn()'s in a way they can "live" with st being NULL (we don't want a null-pointer-deref). What you can see in this commit is the result of this work. Why all this trouble instead of using nftw? The special thing about recurse() is that you tell the function when to recurse() in your fn(). You don't need special flags to tell nftw() to skip the subtree, just to give an example. The only single downside to this is that now, you are not allowed to unconditionally call recurse() from your fn(). It has to be a directory. However, that is a cost I think is easily weighed up by the advantages. Another thing is the history: I added a procedure at the end of the outmost recurse to free the history. This way we don't leak memory. A simple optimization on the side: - if (h->dev == st.st_dev && h->ino == st.st_ino) + if (h->ino == st.st_ino && h->dev == st.st_dev) First compare the likely difference in inode-numbers instead of checking the unlikely condition that the device-numbers are different.
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recurse(*argv, &n, &r);
}
}
Add *fshut() functions to properly flush file streams This has been a known issue for a long time. Example: printf "word" > /dev/full wouldn't report there's not enough space on the device. This is due to the fact that every libc has internal buffers for stdout which store fragments of written data until they reach a certain size or on some callback to flush them all at once to the kernel. You can force the libc to flush them with fflush(). In case flushing fails, you can check the return value of fflush() and report an error. However, previously, sbase didn't have such checks and without fflush(), the libc silently flushes the buffers on exit without checking the errors. No offense, but there's no way for the libc to report errors in the exit- condition. GNU coreutils solve this by having onexit-callbacks to handle the flushing and report issues, but they have obvious deficiencies. After long discussions on IRC, we came to the conclusion that checking the return value of every io-function would be a bit too much, and having a general-purpose fclose-wrapper would be the best way to go. It turned out that fclose() alone is not enough to detect errors. The right way to do it is to fflush() + check ferror on the fp and then to a fclose(). This is what fshut does and that's how it's done before each return. The return value is obviously affected, reporting an error in case a flush or close failed, but also when reading failed for some reason, the error- state is caught. the !!( ... + ...) construction is used to call all functions inside the brackets and not "terminating" on the first. We want errors to be reported, but there's no reason to stop flushing buffers when one other file buffer has issues. Obviously, functionales come before the flush and ret-logic comes after to prevent early exits as well without reporting warnings if there are any. One more advantage of fshut() is that it is even able to report errors on obscure NFS-setups which the other coreutils are unable to detect, because they only check the return-value of fflush() and fclose(), not ferror() as well.
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return fshut(stdout, "<stdout>") || recurse_status;
}