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$FreeBSD: src/lib/libc/db/man/dbm.3,v 1.10 2009/01/30 15:28:35 gabor Exp $
.Dd April 16, 2006 .Dt DBM 3 .Os .Sh NAME .Nm dbm_clearerr , .Nm dbm_close , .Nm dbm_delete , .Nm dbm_dirfno , .Nm dbm_error , .Nm dbm_fetch , .Nm dbm_firstkey , .Nm dbm_nextkey , .Nm dbm_open , .Nm dbm_store .Nd database access functions .Sh SYNOPSIS n ndbm.h .Ft int .Fo dbm_clearerr .Fa "DBM *db" .Fc .Ft void .Fo dbm_close .Fa "DBM *db" .Fc .Ft int .Fo dbm_delete .Fa "DBM *db" .Fa "datum key" .Fc .Ft int .Fo dbm_dirfno .Fa "DBM *db" .Fc .Ft int .Fo dbm_error .Fa "DBM *db" .Fc .Ft datum .Fo dbm_fetch .Fa "DBM *db" .Fa "datum key" .Fc .Ft datum .Fo dbm_firstkey .Fa "DBM *db" .Fc .Ft datum .Fo dbm_nextkey .Fa "DBM *db" .Fc .Ft DBM * .Fo dbm_open .Fa "const char *file" .Fa "int open_flags" .Fa "mode_t file_mode" .Fc .Ft int .Fo dbm_store .Fa "DBM *db" .Fa "datum key" .Fa "datum content" .Fa "int store_mode" .Fc .Sh DESCRIPTION Database access functions. These functions are implemented using .Xr dbopen 3 with a .Xr hash 3 database.
p .Vt datum is declared in n ndbm.h : d -literal typedef struct { char *dptr; int dsize; } datum; .Ed
p The .Fn dbm_open file open_flags file_mode function opens or creates a database file. The .Fa file argument is the basename of the file containing the database; the actual database has a
a .db suffix. I.e., if .Fa file is .Qq Li /home/me/mystuff then the actual database is in the file
a /home/me/mystuff.db . The .Fa open_flags and .Fa file_mode arguments are passed to .Xr open 2 .
q Dv O_RDWR | O_CREAT is a typical value for .Fa open_flags ; .Li 0660 is a typical value for .Fa file_mode . .Dv O_WRONLY is not allowed in .Fa open_flags . The pointer returned by .Fn dbm_open identifies the database and is the .Fa db argument to the other functions. The .Fn dbm_open function returns .Dv NULL and sets .Va errno if there were any errors.
p The .Fn dbm_close db function closes the database.
p The .Fn dbm_store db key content store_mode function inserts or replaces an entry in the database. The .Fa store_mode argument is either .Dv DBM_INSERT or .Dv DBM_REPLACE . If .Fa store_mode is .Dv DBM_INSERT and the database already contains an entry for .Fa key , that entry is not replaced. Otherwise the entry is replaced or inserted. The .Fn dbm_store function normally returns zero but returns 1 if the entry could not be inserted (because .Fa store_mode is .Dv DBM_INSERT , and an entry with .Fa key already exists) or returns -1 and sets .Va errno if there were any errors.
p The .Fn dbm_fetch db key function returns .Dv NULL or the .Fa content corresponding to .Fa key .
p The .Fn dbm_delete db key function deletes the entry for .Fa key . The .Fn dbm_delete function normally returns zero but returns 1 if there was no entry with .Fa key in the database or returns -1 and sets .Va errno if there were any errors.
p The .Fn dbm_firstkey db function returns the first key in the database. The .Fn dbm_nextkey db function returns subsequent keys. The .Fn db_firstkey function must be called before .Fn dbm_nextkey . The order in which keys are returned is unspecified and may appear random. The .Fn dbm_nextkey function returns .Dv NULL after all keys have been returned.
p The .Fn dbm_error db function returns the .Va errno value of the most recent error. The .Fn dbm_clearerr db function resets this value to 0 and returns 0.
p The .Fn dbm_dirfno db function returns the file descriptor to the database. .Sh LEGACY SYNOPSIS .Fd #include <fcntl.h> .Fd #include <ndbm.h>
p The include file n ndbm.h is necessary for all functions.
p .Ft DBM *
.Fo dbm_open .Fa "const char *file" .Fa "int open_flags" .Fa "int file_mode" .Fc ;
p .Fa file_mode has type .Vt int . .Sh SEE ALSO .Xr open 2 , .Xr dbopen 3 , .Xr hash 3 , .Xr compat 5 .Sh STANDARDS These functions (except .Fn dbm_dirfno ) are included in the .St -susv2 .