From: Mikael Magnusson <mikachu@gmail.com>
To: zsh workers <zsh-workers@zsh.org>
Subject: [PATCH 3/4] attr: dynamically allocate memory for attributes
Date: Tue, 3 Nov 2009 19:57:06 +0100 (CET) [thread overview]
Message-ID: <alpine.LNX.2.00.0911031956240.3783@localhost> (raw)
In-Reply-To: <alpine.LNX.2.00.0911031951480.3519@localhost>
If there is a race condition and the attribute grows between the two
calls, we return an error instead of trying again.
---
Doc/Zsh/mod_attr.yo | 5 ++++
Src/Modules/attr.c | 63 ++++++++++++++++++++++++++++++++++-----------------
2 files changed, 47 insertions(+), 21 deletions(-)
diff --git a/Doc/Zsh/mod_attr.yo b/Doc/Zsh/mod_attr.yo
index ed444d0..517bb63 100644
--- a/Doc/Zsh/mod_attr.yo
+++ b/Doc/Zsh/mod_attr.yo
@@ -32,3 +32,8 @@ var(filename). If the optional argument var(parameter) is given, the
list of attributes is set on that parameter instead of being printed to stdout.
)
enditem()
+
+tt(zgetattr) and tt(zlistattr) allocate memory dynamically. If the attribute or
+list of attributes grows between the allocation and the call to get them, they
+return 2. On all other errors, 1 is returned. This way, the calling function can
+check for this case and try again for as long as they want.
diff --git a/Src/Modules/attr.c b/Src/Modules/attr.c
index 1a9c323..bb30ebb 100644
--- a/Src/Modules/attr.c
+++ b/Src/Modules/attr.c
@@ -98,26 +98,37 @@ static int
bin_getattr(char *nam, char **argv, Options ops, UNUSED(int func))
{
int ret = 0;
- int len, slen;
- char value[256];
+ int list_len, val_len, attr_len, slen;
+ char *value;
int symlink = OPT_ISSET(ops, 'h');
unmetafy(*argv, &slen);
unmetafy(*(argv+1), NULL);
- if (xlistxattr(*argv, NULL, 0, symlink) > 0) {
- if (0 < (len = xgetxattr(*argv, *(argv+1), value, 255, symlink))) {
- if (len < 256) {
- value[len] = '\0';
+ list_len = xlistxattr(*argv, NULL, 0, symlink);
+ if (list_len > 0) {
+ val_len = xgetxattr(*argv, *(argv+1), NULL, 0, symlink);
+ if (val_len == 0) {
+ if (*(argv+2))
+ unsetparam(*(argv+2));
+ return 0;
+ }
+ if (val_len > 0) {
+ value = (char *)zalloc(val_len+1);
+ attr_len = xgetxattr(*argv, *(argv+1), value, val_len, symlink);
+ if (attr_len > 0 && attr_len <= val_len) {
+ value[attr_len] = '\0';
if (*(argv+2))
- setsparam(*(argv+2), metafy(value, len, META_DUP));
+ setsparam(*(argv+2), metafy(value, attr_len, META_DUP));
else
printf("%s\n", value);
}
- } else if (len < 0) {
- zwarnnam(nam, "%s: %e", metafy(*argv, slen, META_NOALLOC), errno);
- ret = 1;
+ zfree(value, val_len+1);
}
}
+ if (list_len < 0 || val_len < 0 || attr_len < 0) {
+ zwarnnam(nam, "%s: %e", metafy(*argv, slen, META_NOALLOC), errno);
+ ret = 1 + (attr_len > val_len);
+ }
return ret;
}
@@ -160,41 +171,51 @@ static int
bin_listattr(char *nam, char **argv, Options ops, UNUSED(int func))
{
int ret = 0;
- int len, slen;
- char value[256];
+ int val_len, list_len, slen;
+ char *value;
int symlink = OPT_ISSET(ops, 'h');
unmetafy(*argv, &slen);
- if (0 < (len = xlistxattr(*argv, value, 256, symlink))) {
- if (len < 256) {
+ val_len = xlistxattr(*argv, NULL, 0, symlink);
+ if (val_len == 0) {
+ if (*(argv+1))
+ unsetparam(*(argv+1));
+ return 0;
+ }
+ if (val_len > 0) {
+ value = (char *)zalloc(val_len+1);
+ list_len = xlistxattr(*argv, value, val_len, symlink);
+ if (list_len > 0 && list_len <= val_len) {
char *p = value;
if (*(argv+1)) {
- if (strlen(value) + 1 == len)
- setsparam(*(argv+1), metafy(value, len-1, META_DUP));
+ if (strlen(value) + 1 == list_len)
+ setsparam(*(argv+1), metafy(value, list_len-1, META_DUP));
else {
int arrlen = 0;
char **array = NULL, **arrptr = NULL;
- while (p < &value[len]) {
+ while (p < &value[list_len]) {
arrlen++;
p += strlen(p) + 1;
}
arrptr = array = (char **)zshcalloc((arrlen+1) * sizeof(char *));
p = value;
- while (p < &value[len]) {
+ while (p < &value[list_len]) {
*arrptr++ = metafy(p, -1, META_DUP);
p += strlen(p) + 1;
}
setaparam(*(argv+1), array);
}
- } else while (p < &value[len]) {
+ } else while (p < &value[list_len]) {
printf("%s\n", p);
p += strlen(p) + 1;
}
}
- } else if (len < 0) {
+ zfree(value, val_len+1);
+ }
+ if (val_len < 0 || list_len < 0) {
zwarnnam(nam, "%s: %e", metafy(*argv, slen, META_NOALLOC), errno);
- ret = 1;
+ ret = 1 + (list_len > val_len);
}
return ret;
}
--
1.6.5
next prev parent reply other threads:[~2009-11-03 19:04 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-26 21:55 [wip patch] new zsh/attr module Mikael Magnusson
2009-02-26 22:36 ` Mikael Magnusson
2009-02-27 0:48 ` Mikael Magnusson
2009-03-03 12:12 ` Peter Stephenson
2009-03-03 14:43 ` Mikael Magnusson
2009-03-03 16:35 ` Peter Stephenson
2009-03-03 16:51 ` Mikael Magnusson
2009-03-03 16:55 ` Peter Stephenson
2009-03-03 17:00 ` Mikael Magnusson
2009-11-03 18:52 ` Mikael Magnusson
2009-11-03 18:55 ` [PATCH 1/4] attr: add -h option to operate on symlinks without dereferencing Mikael Magnusson
2009-11-04 10:48 ` Peter Stephenson
2009-11-04 11:01 ` Mikael Magnusson
2009-11-04 11:36 ` Peter Stephenson
2010-09-12 11:12 ` Mikael Magnusson
2009-11-03 18:56 ` [PATCH 2/4] attr: Make zlistattr return an array, zdelattr take several attrs Mikael Magnusson
2009-11-05 6:51 ` [PATCH 2/4] attr: Make zlistattr return an array, zdelattr takeseveral attrs Jun T.
2009-11-05 9:48 ` Mikael Magnusson
2009-11-03 18:57 ` Mikael Magnusson [this message]
2009-11-03 18:57 ` [PATCH 4/4] attr: Use descriptive variables for argv and allow setting values with embedded nuls Mikael Magnusson
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