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libpwdgrp: tweak comments, replace one xmalloc with xzalloc

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2015-01-03 15:15:47 +01:00
parent 908b6e5dfd
commit 31d6734457
1 changed files with 17 additions and 23 deletions
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32
libpwdgrp/pwd_grp.c
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@ -9,38 +9,33 @@
* Rewrite of some parts. Main differences are:
*
* 1) the buffer for getpwuid, getgrgid, getpwnam, getgrnam is dynamically
* allocated and reused by later calls. if ERANGE error pops up it is
* reallocated to the size of the longest line found so far in the
* passwd/group files and reused for later calls.
* allocated and reused by later calls.
* If ENABLE_FEATURE_CLEAN_UP is set the buffers are freed at program
* exit using the atexit function to make valgrind happy.
* 2) the passwd/group files:
* a) must contain the expected number of fields (as per count of field
* delimeters ":") or we will complain with a error message.
* b) leading or trailing whitespace in fields is allowed and handled.
* b) leading or trailing whitespace in fields is stripped.
* c) some fields are not allowed to be empty (e.g. username, uid/gid,
* homedir, shell) and in this case NULL is returned and errno is
* set to EINVAL. This behaviour could be easily changed by
* modifying PW_DEF, GR_DEF, SP_DEF strings (uppercase
* makes a field mandatory).
* d) the string representing uid/gid must be convertible by strtoXX
* functions or NULL is returned and errno is set to EINVAL.
* e) leading or trailing whitespaces in member names and empty members
* are allowed and handled.
* 3) the internal function for getgrouplist uses a dynamically allocated
* buffer and retries with a bigger one in case it is too small;
* 4) the _r functions use the user supplied buffers that are never reallocated
* but use mostly the same common code as the other functions.
* 5) at the moment only the functions really used by busybox code are
* functions, or errno is set to EINVAL.
* e) leading or trailing whitespace in group member names are stripped.
* 3) the internal function for getgrouplist uses dynamically allocated buffer.
* 4) at the moment only the functions really used by busybox code are
* implemented, if you need a particular missing function it should be
* easy to write it by using the internal common code.
*/
#include "libbb.h"
/* S = string not empty, s = string maybe empty, */
/* I = uid,gid, l = long maybe empty, m = members,*/
/* r = reserved */
/* S = string not empty, s = string maybe empty,
* I = uid,gid, l = long maybe empty, m = members,
* r = reserved
*/
#define PW_DEF "SsIIsSS"
#define GR_DEF "SsIm"
#define SP_DEF "Ssllllllr"
@ -99,7 +94,8 @@ static const struct const_passdb const_sp_db = { _PATH_SHADOW, sp_off, SP_DEF, s
/* We avoid having big global data. */
struct statics {
/* It's ok to use one buffer for getpwuid and getpwnam. Manpage says:
/* It's ok to use same buffer (db[0].malloced) for getpwuid and getpwnam.
* Manpage says:
* "The return value may point to a static area, and may be overwritten
* by subsequent calls to getpwent(), getpwnam(), or getpwuid()."
*/
@ -124,9 +120,7 @@ static struct statics *get_S(void)
return ptr_to_statics;
}
/**********************************************************************/
/* Internal functions */
/**********************************************************************/
/* Divide the passwd/group/shadow record in fields
* by substituting the given delimeter
@ -461,7 +455,7 @@ static gid_t* FAST_FUNC getgrouplist_internal(int *ngroups_ptr,
get_S();
/* We alloc space for 8 gids at a time. */
group_list = xmalloc(8 * sizeof(group_list[0]));
group_list = xzalloc(8 * sizeof(group_list[0]));
group_list[0] = gid;
ngroups = 1;