Open System Services System Calls Reference Manual (G06.25+, H06.03+)

creat(2) OSS System Calls Reference Manual
• The owner ID of the file is set to the effective user ID of the process.
• The group ID of the file is determined by the value of the S_ISGID flag in the parent
directory. If S_ISGID is set, then the group ID of the file is set to the group ID of the
parent directory; otherwise, the group ID of the file is set to the effective group ID of the
calling process. If the file is a Guardian file (that is, in the /G file system), the group ID
is set to that of the primary group of the effective user ID.
• The file permission and attribute bits are set to the value of the mode parameter, modified
as listed:
— All bits set in the process file mode creation mask are cleared.
— The set user ID attribute (S_ISUID bit) is cleared.
— The set group ID attribute (S_ISGID bit) is cleared.
If bits other than the file permission and appropriate file-type flags are set in the mode
parameter, errno is set to [EINVAL].
If the file exists and is a regular file that is successfully opened, then:
• The length of the file is truncated to 0 (zero).
• The owner and group of the file are unchanged.
• The set user ID attribute of the file mode is cleared.
The open fails if any of these conditions are true:
• The file supports enforced record locks, and another process has locked a portion of the
file.
• The file does not allow write access.
A program can request some control over when updates should be made permanent for a
regular file opened for write access.
File Type Flags
The file type flags that can be logically ORed into the value specified in the mode parameter are:
S_IFREG Regular file in the OSS file system or in /G, the Guardian file system.
S_ISVTX Sticky bit; used only for directories (cannot be used for files in /G, the Guardian
file system).
S_NONSTOP Regular file in the OSS file system protected by disk process checkpointing.
(Files in /G cannot have this flag set.)
When set, this flag indicates that return from a write operation does not occur
until both the primary and backup disk processes have the data (thereby protect-
ing the data against a single point of failure).
OSS file-system data caching is disabled for write operations on files for which
this flag is set. Performance is slower than when caching is used, but data
integrity protection increases. Performance is faster than when the O_SYNC
flag in the oflag parameter of the open() function is used, but data integrity pro-
tection is less than that provided by O_SYNC use.
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