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author | thomas <thomas@FreeBSD.org> | 2016-02-18 08:44:16 +0000 |
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committer | thomas <thomas@FreeBSD.org> | 2016-02-18 08:44:16 +0000 |
commit | 3b2148e2997b381131bff3e262e5d3b4754fed50 (patch) | |
tree | 3573aca88477cbb3596f847adddab1ca8a6f258e /bin | |
parent | 1d033f316cb6507343722bb7b0d069b0a6062613 (diff) | |
download | FreeBSD-src-3b2148e2997b381131bff3e262e5d3b4754fed50.zip FreeBSD-src-3b2148e2997b381131bff3e262e5d3b4754fed50.tar.gz |
Reorganize the handling all-zeroes terminal block in sparse mode
The intent of the previous code in that case was to force
an explicit write, but the implementation was incorrect, and
as a result the write was never performed. This new implementation
instead uses ftruncate(2) to extend the file with a trailing hole.
Also introduce regression tests for these cases.
PR: 189284
(original PR whose fix introduced this bug)
PR: 207092
Differential Revision: D5248
Reviewed by: sobomax,kib
MFC after: 2 weeks
Diffstat (limited to 'bin')
-rw-r--r-- | bin/dd/Makefile | 13 | ||||
-rw-r--r-- | bin/dd/dd.c | 36 | ||||
-rw-r--r-- | bin/dd/dd.h | 1 | ||||
-rw-r--r-- | bin/dd/gen.c | 13 | ||||
-rw-r--r-- | bin/dd/ref.obs_zeroes | 3 |
5 files changed, 47 insertions, 19 deletions
diff --git a/bin/dd/Makefile b/bin/dd/Makefile index 5f07dbc..6b17d29 100644 --- a/bin/dd/Makefile +++ b/bin/dd/Makefile @@ -24,7 +24,18 @@ test: ${PROG} gen LC_ALL=en_US.US-ASCII hexdump -C | \ diff -I FreeBSD - ${.CURDIR}/ref.${conv} .endfor - @rm -f gen + @${ECHO} "testing sparse file (obs zeroes)" + @./gen 189284 | ./dd ibs=16 obs=8 conv=sparse of=obs_zeroes 2> /dev/null + @hexdump -C obs_zeroes | diff -I FreeBSD - ${.CURDIR}/ref.obs_zeroes + + @${ECHO} "testing spase file (all zeroes)" + @./dd if=/dev/zero of=1M_zeroes bs=1048576 count=1 2> /dev/null + @./dd if=1M_zeroes of=1M_zeroes.1 bs=1048576 conv=sparse 2> /dev/null + @./dd if=1M_zeroes of=1M_zeroes.2 bs=1048576 2> /dev/null + @diff 1M_zeroes 1M_zeroes.1 + @diff 1M_zeroes 1M_zeroes.2 + + @rm -f gen 1M_zeroes* obs_zeroes .if ${MK_TESTS} != "no" SUBDIR+= tests diff --git a/bin/dd/dd.c b/bin/dd/dd.c index 8ae11a7..4c31a5e 100644 --- a/bin/dd/dd.c +++ b/bin/dd/dd.c @@ -77,7 +77,6 @@ STAT st; /* statistics */ void (*cfunc)(void); /* conversion function */ uintmax_t cpy_cnt; /* # of blocks to copy */ static off_t pending = 0; /* pending seek if sparse */ -static off_t last_sp = 0; /* size of last added sparse block */ u_int ddflags = 0; /* conversion options */ size_t cbsz; /* conversion block size */ uintmax_t files_cnt = 1; /* # of files to copy */ @@ -409,6 +408,15 @@ dd_close(void) } if (out.dbcnt || pending) dd_out(1); + + /* + * If the file ends with a hole, ftruncate it to extend its size + * up to the end of the hole (without having to write any data). + */ + if (out.seek_offset > 0 && (out.flags & ISTRUNC)) { + if (ftruncate(out.fd, out.seek_offset) == -1) + err(1, "truncating %s", out.name); + } } void @@ -457,29 +465,27 @@ dd_out(int force) } if (sparse && !force) { pending += cnt; - last_sp = cnt; nw = cnt; } else { if (pending != 0) { - /* If forced to write, and we have no - * data left, we need to write the last - * sparse block explicitly. + /* + * Seek past hole. Note that we need to record the + * reached offset, because we might have no more data + * to write, in which case we'll need to call + * ftruncate to extend the file size. */ - if (force && cnt == 0) { - pending -= last_sp; - assert(outp == out.db); - memset(outp, 0, cnt); - } - if (lseek(out.fd, pending, SEEK_CUR) == - -1) + out.seek_offset = lseek(out.fd, pending, SEEK_CUR); + if (out.seek_offset == -1) err(2, "%s: seek error creating sparse file", out.name); - pending = last_sp = 0; + pending = 0; } - if (cnt) + if (cnt) { nw = write(out.fd, outp, cnt); - else + out.seek_offset = 0; + } else { return; + } } if (nw <= 0) { diff --git a/bin/dd/dd.h b/bin/dd/dd.h index a8b45e5..196f804 100644 --- a/bin/dd/dd.h +++ b/bin/dd/dd.h @@ -54,6 +54,7 @@ typedef struct { const char *name; /* name */ int fd; /* file descriptor */ off_t offset; /* # of blocks to skip */ + off_t seek_offset; /* offset of last seek past output hole */ } IO; typedef struct { diff --git a/bin/dd/gen.c b/bin/dd/gen.c index 9c7571a..d53d8fb 100644 --- a/bin/dd/gen.c +++ b/bin/dd/gen.c @@ -5,13 +5,20 @@ */ #include <stdio.h> +#include <string.h> int -main(int argc __unused, char **argv __unused) +main(int argc, char **argv) { int i; - for (i = 0; i < 256; i++) - putchar(i); + if (argc > 1 && !strcmp(argv[1], "189284")) { + fputs("ABCDEFGH", stdout); + for (i = 0; i < 8; i++) + putchar(0); + } else { + for (i = 0; i < 256; i++) + putchar(i); + } return (0); } diff --git a/bin/dd/ref.obs_zeroes b/bin/dd/ref.obs_zeroes new file mode 100644 index 0000000..473ff7c --- /dev/null +++ b/bin/dd/ref.obs_zeroes @@ -0,0 +1,3 @@ +$FreeBSD$ +00000000 41 42 43 44 45 46 47 48 00 00 00 00 00 00 00 00 |ABCDEFGH........| +00000010 |