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‘seek’ now accepts ‘SEEK_DATA’ and ‘SEEK_HOLE’ where supported.

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* libguile/ports.c (scm_seek): Let SEEK_DATA and SEEK_HOLE through.
(scm_init_ice_9_ports): Define ‘SEEK_DATA’ and ‘SEEK_HOLE’.
* module/ice-9/ports.scm: Export ‘SEEK_DATA’ and ‘SEEK_HOLE’ when
defined.
* test-suite/tests/ports.test ("size of sparse file")
("SEEK_DATA while on data", "SEEK_DATA while in hole")
("SEEK_HOLE while in hole"): New tests.
* NEWS: Update.
This commit is contained in:
Ludovic Courtès 2024-04-15 19:48:10 +02:00
parent 4a0c2433d9
commit 696acfc9e5
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GPG key ID: 090B11993D9AEBB5
5 changed files with 119 additions and 10 deletions
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42
libguile/ports.c
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@ -1,4 +1,4 @@
/* Copyright 1995-2001,2003-2004,2006-2019,2021
/* Copyright 1995-2001,2003-2004,2006-2019,2021,2024
Free Software Foundation, Inc.
This file is part of Guile.
@ -3713,9 +3713,26 @@ SCM_DEFINE (scm_seek, "seek", 3, 0, 0,
"@defvar SEEK_END\n"
"Seek from the end of the file.\n"
"@end defvar\n"
"If @var{fd_port} is a file descriptor, the underlying system\n"
"call is @code{lseek}. @var{port} may be a string port.\n"
"\n"
"On systems that support it, such as GNU/Linux, the following\n"
"constants can be used for @var{whence} to navigate ``holes'' in\n"
"sparse files:\n"
"@defvar SEEK_DATA\n"
"Seek to the next location in the file greater than or equal to\n"
"@var{offset} containing data. If @var{offset} points to data,\n"
"then the file offset is set to @var{offset}.\n"
"@end defvar\n"
"@defvar SEEK_HOLE\n"
"Seek to the next hole in the file greater than or equal to the\n"
"@var{offset}. If @var{offset} points into the middle of a hole,\n"
"then the file offset is set to @var{offset}. If there is no hole\n"
"past @var{offset}, then the file offset is adjusted to the end of\n"
"the file---i.e., there is an implicit hole at the end of any file.\n"
"@end defvar\n"
"\n"
"If @var{fd_port} is a file descriptor, the underlying system call\n"
"is @code{lseek} (@pxref{File Position Primitive,,, libc, The GNU C\n"
"Library Reference Manual}). @var{port} may be a string port.\n"
"\n"
"The value returned is the new position in the file. This means\n"
"that the current position of a port can be obtained using:\n"
"@lisp\n"
@ -3728,7 +3745,14 @@ SCM_DEFINE (scm_seek, "seek", 3, 0, 0,
fd_port = SCM_COERCE_OUTPORT (fd_port);
how = scm_to_int (whence);
if (how != SEEK_SET && how != SEEK_CUR && how != SEEK_END)
if (how != SEEK_SET && how != SEEK_CUR && how != SEEK_END
#ifdef SEEK_DATA
&& how != SEEK_DATA
#endif
#ifdef SEEK_HOLE
&& how != SEEK_HOLE
#endif
)
SCM_OUT_OF_RANGE (3, whence);
if (SCM_OPPORTP (fd_port))
@ -4151,6 +4175,14 @@ scm_init_ice_9_ports (void)
scm_c_define ("SEEK_CUR", scm_from_int (SEEK_CUR));
scm_c_define ("SEEK_END", scm_from_int (SEEK_END));
/* Support for sparse files (glibc). */
#ifdef SEEK_DATA
scm_c_define ("SEEK_DATA", scm_from_int (SEEK_DATA));
#endif
#ifdef SEEK_HOLE
scm_c_define ("SEEK_HOLE", scm_from_int (SEEK_HOLE));
#endif
scm_c_define ("%current-input-port-fluid", cur_inport_fluid);
scm_c_define ("%current-output-port-fluid", cur_outport_fluid);
scm_c_define ("%current-error-port-fluid", cur_errport_fluid);