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getgrnam, getgrnam_r: hledat název databáze v databázi

Originální popis anglicky: getgrnam, getgrnam_r - search group database for a name

Návod, kniha: POSIX Programmer's Manual

STRUČNĚ

#include <grp.h>
 
 
struct group *getgrnam(const char * name);
 
int getgrnam_r(const char *name, struct group *grp, char *buffer,
 
       size_t bufsize, struct group **result);
 

POPIS / INSTRUKCE

The getgrnam() function shall search the group database for an entry with a matching name.
The getgrnam() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.
The getgrnam_r() function shall update the group structure pointed to by grp and store a pointer to that structure at the location pointed to by result. The structure shall contain an entry from the group database with a matching gid or name. Storage referenced by the group structure is allocated from the memory provided with the buffer parameter, which is bufsize bytes in size. The maximum size needed for this buffer can be determined with the {_SC_GETGR_R_SIZE_MAX} sysconf() parameter. A NULL pointer is returned at the location pointed to by result on error or if the requested entry is not found.

NÁVRATOVÁ HODNOTA

The getgrnam() function shall return a pointer to a struct group with the structure defined in <grp.h> with a matching entry if one is found. The getgrnam() function shall return a null pointer if either the requested entry was not found, or an error occurred. On error, errno shall be set to indicate the error.
The return value may point to a static area which is overwritten by a subsequent call to getgrent(), getgrgid(), or getgrnam().
If successful, the getgrnam_r() function shall return zero; otherwise, an error number shall be returned to indicate the error.

CHYBY / ERRORY

The getgrnam() and getgrnam_r() functions may fail if:
EIO
An I/O error has occurred.
EINTR
A signal was caught during getgrnam().
EMFILE
{OPEN_MAX} file descriptors are currently open in the calling process.
ENFILE
The maximum allowable number of files is currently open in the system.
 
The getgrnam_r() function may fail if:
ERANGE
Insufficient storage was supplied via buffer and bufsize to contain the data to be referenced by the resulting group structure.
 
The following sections are informative.

PŘÍKLADY POUŽITÍ

None.

APPLICATION USAGE

Applications wishing to check for error situations should set errno to 0 before calling getgrnam(). If errno is set on return, an error occurred.
The getgrnam_r() function is thread-safe and shall return values in a user-supplied buffer instead of possibly using a static data area that may be overwritten by each call.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SOUVISEJÍCÍ

endgrent() , getgrgid() , the Base Definitions volume of IEEE Std 1003.1-2001, <grp.h>, <limits.h>, <sys/types.h> Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
2003 IEEE/The Open Group
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