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NAME

cgetent, cgetset, cgetmatch, cgetcap, cgetnum, cgetstr, cgetustr, cgetfirst, cgetnext, cgetclose, cgetusedb — capability database access routines

SYNOPSIS

#include <stdlib.h>

int
cgetent(char **buf, char **db_array, const char *name);

int
cgetset(const char *ent);

int
cgetmatch(char *buf, const char *name);

char *
cgetcap(char *buf, const char *cap, int type);

int
cgetnum(char *buf, const char *cap, long *num);

int
cgetstr(char *buf, const char *cap, char **str);

int
cgetustr(char *buf, const char *cap, char **str);

int
cgetfirst(char **buf, char **db_array);

int
cgetnext(char **buf, char **db_array);

int
cgetclose(void);

int
cgetusedb(int usedb);

DESCRIPTION

The cgetent() function extracts the capability record name from the database specified by the null-terminated file array db_array and returns a pointer to a copy of it in buf. cgetent() will first look for files ending in “.db” (see cap_mkdb(1)) before accessing the ASCII version of the capability database. buf must be retained through all subsequent calls to cgetmatch(), cgetcap(), cgetnum(), cgetstr(), and cgetustr(), but may then be free'd. On success 0 is returned, 1 if the returned record contains an unresolved tc expansion, -1 if the requested record couldn't be found, -2 if a system error occurred (couldn't open or read a file, for example) also setting errno, and -3 if a potential reference loop is detected (see tc= comments below).

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 “file” in the database, and is therefore searched first on the call to cgetent(). The entry is passed in ent. If ent is NULL, the current entry is removed from the database. cgetset() must precede the database traversal. It must be called before cgetent(). If a sequential access is being performed (see below), it must be called before the first sequential access call (cgetfirst() or cgetnext()), or be directly preceded by a cgetclose() call. On success 0 is returned and -1 on failure.

cgetmatch() will return 0 if name is one of the names of the capability record buf, -1 if not.

cgetcap() searches the capability record buf for the capability cap with type type. A type is specified using any single character. If a colon (‘:’) is used, an untyped capability will be searched for (see below for explanation of types). A pointer to the value of cap in buf is returned on success or NULL if the requested capability couldn't be found. The end of the capability value is signaled by a ‘:’ or ASCII NUL (see below for capability database syntax).

cgetnum() retrieves the value of the numeric capability cap from the capability record pointed to by buf. The numeric value is returned in the long pointed to by num. On success 0 is returned, -1 if the requested numeric capability couldn't be found.

cgetstr() retrieves the value of the string capability cap from the capability record pointed to by buf. A pointer to a decoded, NUL-terminated, malloc'd copy of the string is returned in the char * pointed to by str. The number of characters in the decoded string (not including the trailing NUL) is returned on success, -1 if the requested string capability couldn't be found, or -2 if a system error was encountered (storage allocation failure).

cgetustr() is identical to cgetstr() except that it does not expand special characters, but rather returns each character of the capability string literally.

cgetfirst() and cgetnext() comprise a function group that provides for sequential access of the null-terminated array of file names, db_array. cgetfirst() returns the first record in the database and resets the access to the first record. cgetnext() returns the next record in the database with respect to the record returned by the previous cgetfirst() or cgetnext() call. If there is no such previous call, the first record in the database is returned. Each record is returned in a malloc'd copy pointed to by buf. tc expansion is done (see tc= comments below). Upon completion of the database 0 is returned; 1 is returned upon successful return of a record with possibly more remaining (the end of the database has not been reached yet); 2 is returned if the record contains an unresolved tc expansion; -1 is returned if an system error occurred; and -2 is returned if a potential reference loop is detected (see tc= comments below). Upon completion of database (0 return), the database is closed.

cgetclose() closes the file descriptor and resets state used for sequential access. If neither the cgetfirst() nor the cgetnext() functions have been called, cgetclose() has no effect. Note that it does not erase the buffer pushed by a call to cgetset(), nor does it free the buffer allocated by cgetent().

cgetusedb() allows the user to specify whether to use or ignore database files ending in “.db”. If usedb is zero, files ending in “.db” will be ignored. If usedb is non-zero, files ending in “.db” will be used in preference to the text version. The default is to process “.db” files. cgetusedb() returns the previous setting.

EXAMPLES

example|an example of binding multiple values to names:\
	:foo%bar:foo^blah:foo@:\
	:abc%xyz:abc^frap:abc$@:\
	:tc=more:

The capability foo has two values bound to it (bar of type ‘%’ and blah of type ‘^’) and any other value bindings are hidden. The capability abc also has two values bound but only a value of type ‘$’ is prevented from being defined in the capability record more.

file1:
 	new|new_record|a modification of "old":\
		:fript=bar:who-cares@:tc=old:blah:tc=extensions:
file2:
	old|old_record|an old database record:\
		:fript=foo:who-cares:glork#200:

The records are extracted by calling cgetent() with file1 preceding file2. In the capability record new in file1, fript=bar overrides the definition of fript=foo interpolated from the capability record old in file2, who-cares@ prevents the definition of any who-cares definitions in old from being seen, glork#200 is inherited from old, and blah and anything defined by the record extensions is added to those definitions in old. Note that the position of the fript=bar and who-cares@ definitions before tc=old is important here. If they were after, the definitions in old would take precedence.

DIAGNOSTICS

cgetent(), cgetset(), cgetmatch(), cgetnum(), cgetstr(), cgetustr(), cgetfirst(), and cgetnext() return a value greater than or equal to 0 on success and a value less than 0 on failure. cgetcap() returns a character pointer on success and a NULL on failure.

cgetent() and cgetset() may fail and set errno for any of the errors specified for the library functions fopen(3), fclose(3), open(2), and close(2).

cgetent(), cgetset(), cgetstr(), and cgetustr() may fail and set errno as follows:

[ENOMEM]

No memory to allocate.

SEE ALSO

cap_mkdb(1), malloc(3)

BUGS

Colon (‘:’) characters cannot be used in names, types, or values.

There are no checks for tc= name loops in cgetent().

The buffer added to the database by a call to cgetset() is not unique to the database but is rather prepended to any database used.