diff --git a/1998/schweikh3/Makefile b/1998/schweikh3/Makefile index 6e3d6b077..1a4cbadd8 100644 --- a/1998/schweikh3/Makefile +++ b/1998/schweikh3/Makefile @@ -58,7 +58,7 @@ ARCH= # Defines that are needed to compile # CDEFINE= -DM0=sizeof -DM1=long -DM2=void \ - -DM3=realloc -DM4=calloc -DM5=free + -DM3=realloc -DM4=calloc -DM5=free -DSZ=32767 # Include files that are needed to compile # diff --git a/1998/schweikh3/README.md b/1998/schweikh3/README.md index 52cd9c9d9..ad2e479d0 100644 --- a/1998/schweikh3/README.md +++ b/1998/schweikh3/README.md @@ -4,10 +4,29 @@ make all ``` +The author stated: + +``` +In the remote event that the input has more than `8192` files with +the same size (on systems where `sizeof (char *) == 4`, or `4096` when +`sizeof (char *) == 8`), increase the manifest constant 32767 on line +31. +``` + +so we changed the constant to be `SZ` defined in the Makefile. To change the +value you can do something like: + +```sh +make clobber CDEFINE="-DM0=sizeof -DM1=long -DM2=void \ + -DM3=realloc -DM4=calloc -DM5=free -DSZ=55555" all +``` + +or whatever you wish to redefine it to. + ## To use: -If "dir" is the directory (or a directory tree) where you keep +If `dir` is the directory (or a directory tree) where you keep all your favorite pictures off the Internet or from `alt.binaries.pictures.*`, do @@ -15,7 +34,7 @@ all your favorite pictures off the Internet or from find dir -type f -print | ./samefile ``` -Maybe you will not need to buy another 10 Gb disk to store them. :-) +Maybe you will not need to buy another 10 GB disk to store them. :-) ### Try: @@ -23,20 +42,14 @@ Maybe you will not need to buy another 10 Gb disk to store them. :-) If you're in this winning entry's directory: ```sh -find . -type f -print | ./samefile +./try.sh ``` -Notice that the tool finds a duplicate file, that of the man page. +Notice that the tool finds some files that are duplicates. ## Judges' remarks: -Try this: - -```sh -./try.sh -``` - This program is not as smart as to detect identity of JPEG files with the same picture but with different compression levels. On the other hand compression can make a thing look/sound/feel different so these probably aren't duplicates @@ -56,7 +69,7 @@ Thank God the IEEE does not standardize a coding style... ### What this program does This is best explained in the man page. The troff source for this -man page can be found in the file samefile.1. To render try: +man page can be found in the file [samefile.1](samefile.1). To render try: ```sh `man ./samefile.1 @@ -65,23 +78,24 @@ man page can be found in the file samefile.1. To render try: Otherwise: -**SAMEFILE(1) User Manuals SAMEFILE(1)** +### SAMEFILE(1) User Manuals SAMEFILE(1) -**NAME** +#### NAME - **samefile** - find identical files +`samefile` - find identical files -**SYNOPSIS** +#### SYNOPSIS - ./samefile - +```sh +./samefile +``` -**DESCRIPTION** +#### DESCRIPTION `samefile` reads a list of file names (one file name per -line) from `stdin`. For each file name pair with identical +line) from `stdin`. For each file name pair with identical contents, a line consisting of six tab separated fields is output: The size in bytes, two file names, the character `=` if the two files are on the same device, `X` otherwise, @@ -104,10 +118,10 @@ binary tree. In the second stage all files having the same size are compared against each other. The rules of mathematical logic are applied to reduce work and output noise: if -files A, B, and C have the same size and samefile finds -that A = B and A = C then it will not compare B against C -(and will not output a line for B and C) but only for A = -B and A = C. The algorithm will detect equality across +files `A`, `B`, and `C` have the same size and samefile finds +that `A = B` and `A = C` then it will not compare `B` against `C` +(and will not output a line for `B` and `C`) but only for `A = +B` and `A = C`. The algorithm will detect equality across arbitrarily long chains. Note however, that because only the first filename per inode gets into the first stage, the output for a group of identical files with different @@ -116,13 +130,13 @@ identical files of size 100 in an inode group consisting of the three inodes with numbers 10, 20 and 30: ```sh - $ ls -i # output edited for readability: - 10 file1 20 file4 30 file6 - 10 file2 20 file5 - 10 file3 - $ ls | ./samefile - 100 file1 file4 = 3 2 - 100 file1 file6 = 3 1 +$ ls -i # output edited for readability: + 10 file1 20 file4 30 file6 + 10 file2 20 file5 + 10 file3 +$ ls | ./samefile +100 file1 file4 = 3 2 +100 file1 file6 = 3 1 ``` The sum of the sizes in the first column is the amount of @@ -135,24 +149,24 @@ Note that it is not enough to just remove `file4` and `file6` exists.) -**LIMITATIONS** +#### LIMITATIONS `samefile` was written with no limits in mind. The number of input lines is unlimited. The size of the actual files is only limited by available virtual memory needed to compare one pair of files. The only hard limit is the constraint -that there should not be more than about 8192 files having +that there should not be more than about `8192` files having the same size. Experience has shown that there are rarely more than a couple dozen files of the same size. -**EXAMPLES** +#### EXAMPLES For everybody: What are the duplicates under my home directory? ```sh - $ find $HOME | ./samefile +find $HOME | ./samefile ``` For the sysadmin folks: @@ -160,23 +174,23 @@ For the sysadmin folks: Report all duplicate files under /usr larger than 16k: ```sh - $ find /usr -size +16384c -a -type f | ./samefile +find /usr -size +16384c -a -type f | ./samefile ``` For the ftp and WWW admins: How much space is wasted below our site's /pub directory? ```sh - $ find /pub -type f | samefile | awk '{sum += $1} END {print sum}' +find /pub -type f | samefile | awk '{sum += $1} END {print sum}' ``` -**EXIT STATUS** +#### EXIT STATUS If `samefile` runs out of memory the exit status is 1, zero otherwise. -**SEE ALSO** +#### SEE ALSO `find(1)`, `ln(1)`, `rm(1)` @@ -194,19 +208,19 @@ otherwise. of files across arbitrarily long chains? In my private unobfuscated source there are 17 lines describing just that. A classical case for the well known `/* You're not supposed to understand this */` comment. -- Would Dijkstra consider this goto harmful? -- The only string literal is split in more than a dozen substrings +- Would Dijkstra consider this `goto` harmful? +- The only string literal is split in more than a dozen substrings. - For the task at hand the code is pretty terse. Some dynamic memory is even freed as soon as it's no longer needed. I have tried to make the preprocessor directives as short as possible. This means - no spaces after #include and no spaces after some of the macro + no spaces after `#include` and no spaces after some of the macro names. Are you an algorithms guru? If so you should know why the output -appears sorted without any use of `qsort()` or `system("sort")`. +appears sorted without any use of `qsort(3)` or `system("sort")`. Rewrite (hah!) the program to use memory mapping of files instead -of `read()`. Does this affect performance noticeably? +of `read(2)`. Does this affect performance noticeably? It's easy to write a script that takes `samefile`'s output and hard links (or symlinks) identical files. Writing such a script is @@ -214,11 +228,11 @@ left as an exercise for the deobfuscator. When you run `samefile` on some directory tree, try to estimate how much you think it will find. Is the actual result anywhere -near your estimate? How many copies of the GPL COPYING file +near your estimate? How many copies of the GPL `COPYING` file are there on your filesystems? :-) -In the remote event that the input has more than 8192 files with -the same size (on systems where `sizeof (char *) == 4`, or 4096 when +In the remote event that the input has more than `8192` files with +the same size (on systems where `sizeof (char *) == 4`, or `4096` when `sizeof (char *) == 8`), increase the manifest constant 32767 on line 31. diff --git a/1998/schweikh3/schweikh3.c b/1998/schweikh3/schweikh3.c index 8a10fd234..ef8aa1c09 100644 --- a/1998/schweikh3/schweikh3.c +++ b/1998/schweikh3/schweikh3.c @@ -28,7 +28,7 @@ /* HE WHO SAYS */ -Z I A<:32767/ M0(I )]; Z g stat S,T; Z size_t y B f{ +Z I A<: SZ/ M0(I )]; Z g stat S,T; Z size_t y B f{ I n ; g f * x ; dev_t d ; ino_t i; } f B t{ M1 s,c; f *l; g t*L,*R; } t; D(a,t)D(E ,f)Z t*J(t*p,I n){ H! p){ p= a(); p _ s =S O; p _ c=1; p _ L=p _ R=0; diff --git a/1998/schweikh3/try.sh b/1998/schweikh3/try.sh index 978dc6776..4cc96b92c 100755 --- a/1998/schweikh3/try.sh +++ b/1998/schweikh3/try.sh @@ -12,3 +12,6 @@ echo "$ ln -f file3 file4" ln -f file3 file4 echo "$ find . -type f -name 'file?' | ./samefile" find . -type f -name 'file?' | ./samefile + +echo "find . -type f -print | ./samefile" 1>&2 +find . -type f -print | ./samefile diff --git a/thanks-for-fixes.md b/thanks-for-fixes.md index ff3fee464..2ec1643bc 100644 --- a/thanks-for-fixes.md +++ b/thanks-for-fixes.md @@ -2163,6 +2163,19 @@ command. Cody also made the Makefile rule `all` symlink the entry to `samefile` as that is the name of the program. +The author stated that: + +``` +In the remote event that the input has more than `8192` files with +the same size (on systems where `sizeof (char *) == 4`, or `4096` when +`sizeof (char *) == 8`), increase the manifest constant 32767 on line +31. +``` + +so Cody changed the constant to a macro in the Makefile called `SZ` so one can +more easily do this (though it indeed seems highly unlikely). See the README.md +for more details. + There actually is a web page for the tool and this was added to the author information for the entry. It has not been added to any JSON file. @@ -2170,12 +2183,13 @@ information for the entry. It has not been added to any JSON file. ## [1998/tomtorfs](1998/tomtorfs/tomtorfs.c) ([README.md](1998/tomtorfs/README.md])) Cody fixed the assumption that `EOF` is `-1` (the author noted that it assumes -it is `-1` but the standard only guarantees that it's a value `< 0`) and that 1 -is a valid code to return failure (it seems unlikely that it wouldn't be but -since the author suggested it it was changed to `EXIT_FAILURE`). To make it so -the lines end at the same columns as the original the `EXIT_FAILURE` change was -done by redefining `exit(3)` to be `exit(a) return EXIT_FAILURE` and `1` was -passed to it (`return` was used because the original program had `return 1`). +it is `-1` and it's indeed a valid concern as the standard only guarantees that +it's a value `< 0`) and that `1` is a valid code to return failure (it seems +unlikely that it wouldn't be but since the author suggested it it was changed to +`EXIT_FAILURE`). To make it so the lines end at the same columns as the original +the `EXIT_FAILURE` change was done by redefining `exit(3)` to be `exit(a) return +EXIT_FAILURE` and `1` was passed to it (`return` was used because the original +program had `return 1`). Cody also added the [try.sh](1998/tomtorfs/try.sh) script to try out a few commands that we recommended.