Copyright (c) 1992, 1993
The Regents of the University of California. All rights reserved.
This code is derived from software contributed to Berkeley by
Casey Leedom of Lawrence Livermore National Laboratory.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
@(#)getcap.3 8.4 (Berkeley) 5/13/94
.Dd April 5, 2012 .Dt CGETCAP 3 .Os .Sh NAME .Nm cgetent , .Nm cgetset , .Nm cgetmatch , .Nm cgetcap , .Nm cgetnum , .Nm cgetstr , .Nm cgetustr , .Nm cgetfirst , .Nm cgetnext , .Nm cgetclose , .Nm csetexpandtc .Nd capability database access routines .Sh LIBRARY .Lb libc .Sh SYNOPSIS n stdlib.h .Ft int .Fn cgetent "char **buf" "const char * const *db_array" "const char *name" .Ft int .Fn cgetset "const char *ent" .Ft int .Fn cgetmatch "const char *buf" "const char *name" .Ft char * .Fn cgetcap "char *buf" "const char *cap" "int type" .Ft int .Fn cgetnum "char *buf" "const char *cap" "long *num" .Ft int .Fn cgetstr "char *buf" "const char *cap" "char **str" .Ft int .Fn cgetustr "char *buf" "const char *cap" "char **str" .Ft int .Fn cgetfirst "char **buf" "const char * const *db_array" .Ft int .Fn cgetnext "char **buf" "const char * const *db_array" .Ft int .Fn cgetclose "void" .Ft void .Fn csetexpandtc "int expandtc" .Sh DESCRIPTION .Fn cgetent extracts the capability .Fa name from the database specified by the .Dv NULL terminated file array .Fa db_array and returns a pointer to a .Xr malloc 3 Ap d copy of it in .Fa buf . .Fn cgetent will first look for files ending in
a .db (see .Xr cap_mkdb 1 ) before accessing the .Tn ASCII file.
p .Fa buf must be retained through all subsequent calls to .Fn cgetmatch , .Fn cgetcap , .Fn cgetnum , .Fn cgetstr , and .Fn cgetustr , but may then be .Xr free 3 Ap d .
p On success 0 is returned, 1 if the returned record contains an unresolved .Qq tc expansion, -1 if the requested record couldn't be found, -2 if a system error was encountered (couldn't open/read a file, etc.) also setting .Va errno , and -3 if a potential reference loop is detected (see .Qq tc=name comments below).
p .Fn cgetset enables the addition of a character buffer containing a single capability record entry to the capability database. Conceptually, the entry is added as the first .Dq file in the database, and is therefore searched first on the call to .Fn cgetent . The entry is passed in .Fa ent . If .Fa ent is .Dv NULL , the current entry is removed from the database.
p .Fn cgetset must precede the database traversal. It must be called before the .Fn cgetent call. If a sequential access is being performed (see below), it must be called before the first sequential access call
o .Fn cgetfirst or .Fn cgetnext
c , or be directly preceded by a .Fn cgetclose call. On success 0 is returned and -1 on failure.
p .Fn cgetmatch will return 0 if .Fa name is one of the names of the capability record .Fa buf , -1 if not.
p .Fn cgetcap searches the capability record .Fa buf for the capability .Fa cap with type .Fa type . A .Fa type is specified using any single character. If a colon
q Sq : is used, an untyped capability will be searched for (see below for explanation of types). A pointer to the value of .Fa cap in .Fa buf is returned on success, .Dv NULL if the requested capability couldn't be found. The end of the capability value is signaled by a .Sq : . See .Xr capfile 5 for a description of the capability syntax.
p .Fn cgetnum retrieves the value of the numeric capability .Fa cap from the capability record pointed to by .Fa buf . The numeric value is returned in the .Ft long pointed to by .Fa num . 0 is returned on success, -1 if the requested numeric capability couldn't be found.
p .Fn cgetstr retrieves the value of the string capability .Fa cap from the capability record pointed to by .Fa buf . A pointer to a decoded, .Dv NUL terminated, .Xr malloc 3 Ap d copy of the string is returned in the .Ft char * pointed to by .Fa str . The number of characters in the decoded string not including the trailing .Dv NUL is returned on success, -1 if the requested string capability couldn't be found, -2 if a system error was encountered (storage allocation failure).
p .Fn cgetustr is identical to .Fn cgetstr except that it does not expand special characters, but rather returns each character of the capability string literally.
p .Fn cgetfirst , .Fn cgetnext , comprise a function group that provides for sequential access of the .Dv NULL pointer terminated array of file names, .Fa db_array . .Fn cgetfirst returns the first record in the database and resets the access to the first record. .Fn cgetnext returns the next record in the database with respect to the record returned by the previous .Fn cgetfirst or .Fn cgetnext call. If there is no such previous call, the first record in the database is returned. Each record is returned in a .Xr malloc 3 Ap d copy pointed to by .Fa buf . .Qq tc expansion is done (see .Qq tc=name comments below).
p Upon completion of the database 0 is returned, 1 is returned upon successful return of record with possibly more remaining (we haven't reached the end of the database yet), 2 is returned if the record contains an unresolved .Qq tc expansion, -1 is returned if an system error occurred, and -2 is returned if a potential reference loop is detected (see .Qq tc=name comments below). Upon completion of database (0 return) the database is closed.
p .Fn cgetclose closes the sequential access and frees any memory and file descriptors being used. Note that it does not erase the buffer pushed by a call to .Fn cgetset . .Sh CAPABILITY DATABASE SEMANTICS Capability records describe a set of (name, value) bindings. Names may have multiple values bound to them. Different values for a name are distinguished by their .Fa types . .Fn cgetcap will return a pointer to a value of a name given the capability name and the type of the value.
p The types .Sq # and .Sq = are conventionally used to denote numeric and string typed values, but no restriction on those types is enforced. The functions .Fn cgetnum and .Fn cgetstr can be used to implement the traditional syntax and semantics of .Sq # and .Sq = . Typeless capabilities are typically used to denote boolean objects with presence or absence indicating truth and false values respectively. This interpretation is conveniently represented by:
p .Dl "(getcap(buf, name, ':') != NULL)"
p A special capability, .Qq tc=name , is used to indicate that the record specified by .Fa name should be substituted for the .Qq tc capability. .Qq tc capabilities may interpolate records which also contain .Qq tc capabilities and more than one .Qq tc capability may be used in a record. A .Qq tc expansion scope (i.e. where the argument is searched for) contains the file in which the .Qq tc is declared and all subsequent files in the file array.
p .Fn csetexpandtc can be used to control if .Qq tc expansion is performed or not. .Sh RETURN VALUES .Fn cgetent , .Fn cgetset , .Fn cgetmatch , .Fn cgetnum , .Fn cgetstr , .Fn cgetustr , .Fn cgetfirst , and .Fn cgetnext return a value greater than or equal to 0 on success and a value less than 0 on failure. .Fn cgetcap returns a character pointer on success and a .Dv NULL on failure.
p .Fn cgetclose , .Fn cgetent , .Fn cgetfirst , and .Fn cgetnext may fail and set .Va errno for any of the errors specified for the library functions: .Xr fopen 3 , .Xr fclose 3 , .Xr open 2 , and .Xr close 2 .
p .Fn cgetent , .Fn cgetset , .Fn cgetstr , and .Fn cgetustr may fail and set .Va errno as follows: l -tag -width Er t Bq Er ENOMEM No memory to allocate. .El .Sh SEE ALSO .Xr cap_mkdb 1 , .Xr malloc 3 , .Xr capfile 5 .Sh BUGS There are no checks for .Qq tc=name loops in .Fn cgetent .
p The buffer added to the database by a call to .Fn cgetset is not unique to the database but is rather prepended to any database used.
Indexes created Sun Nov 02 07:10:05 GMT 2025