From 78e51a8c6678b6e3dff3d619aa786669f531f4bc Mon Sep 17 00:00:00 2001 From: rsc Date: Fri, 14 Jan 2005 03:45:44 +0000 Subject: checkpoint --- man/man3/open.html | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100644 man/man3/open.html (limited to 'man/man3/open.html') diff --git a/man/man3/open.html b/man/man3/open.html new file mode 100644 index 00000000..64f85c55 --- /dev/null +++ b/man/man3/open.html @@ -0,0 +1,130 @@ + +open(3) - Plan 9 from User Space + + + + +
+
+
OPEN(3)OPEN(3) +
+
+

NAME
+ +
+ + open, create, close – open a file for reading or writing, create + file
+ +
+

SYNOPSIS
+ +
+ + #include <u.h>
+ #include <libc.h> +
+ + int open(char *file, int omode) +
+ + int create(char *file, int omode, ulong perm) +
+ + int close(int fd)
+ +
+

DESCRIPTION
+ +
+ + Open opens the file for I/O and returns an associated file descriptor. + Omode is one of OREAD, OWRITE, ORDWR, or OEXEC, asking for permission + to read, write, read and write, or execute, respectively. In addition, + there are three values that can be ORed with the omode: OTRUNC + says to truncate the file to zero length + before opening it; OCEXEC says to close the file when an exec(3) + or execl system call is made; and ORCLOSE says to remove the file + when it is closed (by everyone who has a copy of the file descriptor). + Open fails if the file does not exist or the user does not have + permission to open it for the requested purpose (see + stat(3) for a description of permissions). The user must have + write permission on the file if the OTRUNC bit is set. For the + open system call (unlike the implicit open in exec(3)), OEXEC + is actually identical to OREAD. +
+ + Create creates a new file or prepares to rewrite an existing file, + opens it according to omode (as described for open), and returns + an associated file descriptor. If the file is new, the owner is + set to the userid of the creating process group; the group to + that of the containing directory; the permissions to perm ANDed + with + the permissions of the containing directory. If the file already + exists, it is truncated to 0 length, and the permissions, owner, + and group remain unchanged. The created file is a directory if + the DMDIR bit is set in perm, an exclusive-use file if the DMEXCL + bit is set, and an append-only file if the DMAPPEND bit is set. + Exclusive-use files may be open for I/O by only one client at + a time, but the file descriptor may become invalid if no I/O is + done for an extended period; see open(9p). +
+ + Create fails if the path up to the last element of file cannot + be evaluated, if the user doesn’t have write permission in the + final directory, if the file already exists and does not permit + the access defined by omode, of if there there are no free file + descriptors. In the last case, the file may be created even when + an error is + returned. +
+ + Since create may succeed even if the file exists, a special mechanism + is necessary for those applications that require an atomic create + operation. If the OEXCL (0x1000) bit is set in the mode for a + create, the call succeeds only if the file does not already exist; + see open(9p) for details. +
+ + Close closes the file associated with a file descriptor. Provided + the file descriptor is a valid open descriptor, close is guaranteed + to close it; there will be no error. Files are closed automatically + upon termination of a process; close allows the file descriptor + to be reused.
+ +
+

SOURCE
+ +
+ + /usr/local/plan9/src/lib9
+ +
+

SEE ALSO
+ +
+ + intro(3), stat(3)
+ +
+

DIAGNOSTICS
+ +
+ + These functions set errstr.
+ +
+ +

 +
+
+ + +
+
+
+Space Glenda +
+
+ + -- cgit v1.2.3