- import of strongswan-2.7.0
- applied patch for charon
This commit is contained in:
Martin Willi
@@ -0,0 +1,182 @@
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.TH IPSEC_OPTIONSFROM 3 "16 Oct 1998"
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.\" RCSID $Id: optionsfrom.3,v 1.1 2004/03/15 20:35:26 as Exp $
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.SH NAME
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ipsec optionsfrom \- read additional ``command-line'' options from file
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.SH SYNOPSIS
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.B "#include <freeswan.h>
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.sp
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.B "const char *optionsfrom(char *filename, int *argcp,"
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.ti +1c
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.B "char ***argvp, int optind, FILE *errsto);"
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.SH DESCRIPTION
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.I Optionsfrom
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is called from within a
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.IR getopt_long (3)
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scan,
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as the result of the appearance of an option (preferably
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.BR \-\-optionsfrom )
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to insert additional ``command-line'' arguments
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into the scan immediately after
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the option.
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Typically this would be done to pick up options which are
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security-sensitive and should not be visible to
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.IR ps (1)
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and similar commands,
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and hence cannot be supplied as part
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of the actual command line or the environment.
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.PP
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.I Optionsfrom
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reads the additional arguments from the specified
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.IR filename ,
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allocates a new argument vector to hold pointers to the existing
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arguments plus the new ones,
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and amends
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.I argc
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and
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.I argv
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(via the pointers
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.I argcp
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and
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.IR argvp ,
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which must point to the
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.I argc
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and
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.I argv
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being supplied to
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.IR getopt_long (3))
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accordingly.
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.I Optind
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must be the index, in the original argument vector,
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of the next argument.
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.PP
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If
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.I errsto
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is NULL,
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.I optionsfrom
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returns NULL for success and
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a pointer to a string-literal error message for failure;
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see DIAGNOSTICS.
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If
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.I errsto
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is non-NULL and an error occurs,
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.I optionsfrom
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prints a suitable complaint onto the
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.I errsto
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descriptor and invokes
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.I exit
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with an exit status of 2;
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this is a convenience for cases where more sophisticated
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responses are not required.
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.PP
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The text of existing arguments is not disturbed by
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.IR optionsfrom ,
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so pointers to them and into them remain valid.
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.PP
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The file of additional arguments is an ASCII text file.
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Lines consisting solely of white space,
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and lines beginning with
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.BR # ,
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are comments and are ignored.
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Otherwise, a line which does not begin with
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.BR \-
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is taken to be a single argument;
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if it both begins and ends with double-quote ("),
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those quotes are stripped off (note, no other processing is done within
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the line!).
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A line beginning with
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.B \-
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is considered to contain multiple arguments separated by white space.
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.PP
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Because
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.I optionsfrom
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reads its entire file before the
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.IR getopt_long (3)
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scan is resumed, an
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.I optionsfrom
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file can contain another
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.B \-\-optionsfrom
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option.
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Obviously, infinite loops are possible here.
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If
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.I errsto
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is non-NULL,
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.I optionsfrom
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considers it an error to be called more than 100 times.
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If
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.I errsto
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is NULL,
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loop detection is up to the caller
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(and the internal loop counter is zeroed out).
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.SH EXAMPLE
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A reasonable way to invoke
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.I optionsfrom
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would be like so:
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.PP
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.nf
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.ft B
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#include <getopt.h>
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struct option opts[] = {
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/* ... */
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"optionsfrom", 1, NULL, '+',
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/* ... */
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};
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int
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main(argc, argv)
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int argc;
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char *argv[];
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{
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int opt;
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extern char *optarg;
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extern int optind;
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while ((opt = getopt_long(argc, argv, "", opts, NULL)) != EOF)
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switch (opt) {
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/* ... */
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case '+': /* optionsfrom */
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optionsfrom(optarg, &argc, &argv, optind, stderr);
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/* does not return on error */
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break;
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/* ... */
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}
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/* ... */
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.ft
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.fi
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.SH SEE ALSO
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getopt_long(3)
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.SH DIAGNOSTICS
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Errors in
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.I optionsfrom
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are:
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unable to open file;
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attempt to allocate temporary storage for argument or
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argument vector failed;
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read error in file;
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line too long.
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.SH HISTORY
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Written for the FreeS/WAN project by Henry Spencer.
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.SH BUGS
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The double-quote convention is rather simplistic.
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.PP
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Line length is currently limited to 1023 bytes,
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and there is no continuation convention.
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.PP
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The restriction of error reports to literal strings
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(so that callers don't need to worry about freeing them or copying them)
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does limit the precision of error reporting.
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.PP
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The error-reporting convention lends itself
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to slightly obscure code,
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because many readers will not think of NULL as signifying success.
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.PP
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There is a certain element of unwarranted chumminess with
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the insides of
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.IR getopt_long (3)
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here.
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No non-public interfaces are actually used, but
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.IR optionsfrom
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does rely on
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.IR getopt_long (3)
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being well-behaved in certain ways that are not actually
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promised by the specs.
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