[COMMIT] Interpret a numeric APPEND as a position for lseek(), #'write-region-internal

APPROVE COMMIT NOTE: This patch has been committed # HG changeset patch # User Aidan Kehoe <kehoea(a)parhasard.net&gt; # Date 1523343822 -3600 # Tue Apr 10 08:03:42 2018 +0100 # Node ID f101d3bd2814d0d11a2ff4ea21f7b80790d508fb # Parent f45199815d5daab32f0943a69987fdd686593289 Interpret a numeric APPEND as a position for lseek(), #'write-region-internal src/ChangeLog addition: 2018-04-10 Aidan Kehoe <kehoea(a)parhasard.net&gt; * fileio.c (lisp_to_off_t): New function. Decode a Lisp_Object into an OFF_T. Accept floats as well as integers, as does GNU (they have more need to, because they don't have bignums) * fileio.c (Finsert_file_contents_internal): Use it here. * fileio.c (Fwrite_region_internal): Interpret a numeric APPEND argument as specifying a byte offset in the output file to seek to before writing. lisp/ChangeLog addition: 2018-04-10 Aidan Kehoe <kehoea(a)parhasard.net&gt; * code-files.el (write-region): Document that APPEND can now be a numeric offset, indicating a point to seek to. diff -r f45199815d5d -r f101d3bd2814 lisp/ChangeLog --- a/lisp/ChangeLog Sat Apr 07 21:40:47 2018 +0100 +++ b/lisp/ChangeLog Tue Apr 10 08:03:42 2018 +0100 ＠＠ -1,3 +1,9 ＠＠ +2018-04-10 Aidan Kehoe <kehoea(a)parhasard.net&gt; + + * code-files.el (write-region): + Document that APPEND can now be a numeric offset, indicating a + point to seek to. + 2018-02-18 Aidan Kehoe <kehoea(a)parhasard.net&gt; * simple.el (no-case-regexp-p): diff -r f45199815d5d -r f101d3bd2814 lisp/code-files.el --- a/lisp/code-files.el Sat Apr 07 21:40:47 2018 +0100 +++ b/lisp/code-files.el Tue Apr 10 08:03:42 2018 +0100 ＠＠ -597,8 +597,8 ＠＠ When called from a program, takes three required arguments: START, END and FILENAME. START and END are buffer positions. -APPEND, if non-nil, means append to existing file contents (if any), else - the file's existing contents are replaced by the specified region. +APPEND, if non-nil, means append to existing file contents (if any). If it is +a byte file offset, seek to that point before writing. VISIT, if non-nil, should be a string naming a file. The buffer is marked as visiting VISIT. VISIT is also the file name to lock and unlock for clash detection. diff -r f45199815d5d -r f101d3bd2814 src/ChangeLog --- a/src/ChangeLog Sat Apr 07 21:40:47 2018 +0100 +++ b/src/ChangeLog Tue Apr 10 08:03:42 2018 +0100 ＠＠ -1,3 +1,15 ＠＠ +2018-04-10 Aidan Kehoe <kehoea(a)parhasard.net&gt; + + * fileio.c (lisp_to_off_t): New function. + Decode a Lisp_Object into an OFF_T. Accept floats as well as + integers, as does GNU (they have more need to, because they don't + have bignums) + * fileio.c (Finsert_file_contents_internal): + Use it here. + * fileio.c (Fwrite_region_internal): + Interpret a numeric APPEND argument as specifying a byte offset in + the output file to seek to before writing. + 2018-04-07 Aidan Kehoe <kehoea(a)parhasard.net&gt; * fileio.c (Fsubstitute_in_file_name): Fixup some whitespace here. diff -r f45199815d5d -r f101d3bd2814 src/fileio.c --- a/src/fileio.c Sat Apr 07 21:40:47 2018 +0100 +++ b/src/fileio.c Tue Apr 10 08:03:42 2018 +0100 ＠＠ -167,6 +167,54 ＠＠ return build_extstring (ret, Qstrerror_encoding); } +static OFF_T +lisp_to_off_t (Lisp_Object offset) +{ + OFF_T result; + double v; + + if (FIXNUMP (offset)) + { + type_checking_assert (FIXNUM_VALBITS <= + (sizeof (OFF_T) * BITS_PER_CHAR)); + return XREALFIXNUM (offset); + } +#ifdef HAVE_BIGNUM + if (BIGNUMP (offset)) + { + if (bignum_fits_emacs_int_p (XBIGNUM_DATA (offset))) + { + type_checking_assert (BITS_PER_EMACS_INT <= + (sizeof (OFF_T) * BITS_PER_CHAR)); + return bignum_to_emacs_int (XBIGNUM_DATA (offset)); + } + else if (sizeof (OFF_T) == sizeof (long long) + && bignum_fits_llong_p (XBIGNUM_DATA (offset))) + { + return bignum_to_llong (XBIGNUM_DATA (offset)); + } + else if (sizeof (OFF_T) == sizeof (unsigned long long) + && (OFF_T)(-1) != -1 + && bignum_fits_ullong_p (XBIGNUM_DATA (offset))) + { + return bignum_to_ullong (XBIGNUM_DATA (offset)); + } + } +#endif + + v = extract_float (offset); + result = v; + + if (result == v) /* Value bits preserved? */ + { + return result; + } + + wtaerror ("Offset not supported", offset); + RETURN_NOT_REACHED (-1); +} + + static Lisp_Object close_file_unwind (Lisp_Object fd) { ＠＠ -2973,13 +3021,14 ＠＠ } #endif /* S_IFREG */ - if (!NILP (start)) - CHECK_NATNUM (start); - else - start = Qzero; - - if (!NILP (end)) - CHECK_NATNUM (end); + if (NILP (start)) + { + start = Qzero; + } + else if (lisp_to_off_t (start) < 0) + { + start = wrong_type_argument (Qnatnump, start); + } if (fd < 0) { ＠＠ -3146,7 +3195,6 ＠＠ /* Arrange to read only the nonmatching middle part of the file. */ start = make_integer (same_at_start - BYTE_BUF_BEGV (buf)); end = make_integer (st.st_size - (BYTE_BUF_ZV (buf) - same_at_end)); - buffer_delete_range (buf, same_at_start, same_at_end, !NILP (visit) ? INSDEL_NO_LOCKING : 0); /* Insert from the file at the proper position. */ ＠＠ -3159,29 +3207,17 ＠＠ Lisp_Object args[] = { end, start }; Lisp_Object diff = Fminus (countof (args), args); - /* Make sure point-max won't overflow after this insertion. */ - if (FIXNUMP (diff)) - { - total = XREALFIXNUM (diff); - } -#ifdef HAVE_BIGNUM - else if (bignum_fits_emacs_int_p (XBIGNUM_DATA (diff))) + total = lisp_to_off_t (diff); + + if (total < 0) { - total = bignum_to_emacs_int (XBIGNUM_DATA (diff)); + dead_wrong_type_argument (Qnatnump, make_integer (total)); } -#endif - else - { - /* Doesn't fit in an EMACS_INT, which means doesn't fit in a - Bytecount, which means we should error. */ - goto unreasonably_large; - } - + + /* Make sure point-max won't overflow after this insertion. */ if ((total > ((Bytecount) (~((EMACS_UINT) 0) >> 1)))) { - unreasonably_large: - out_of_memory ("Maximum buffer byte size exceeded", - diff); + out_of_memory ("Maximum buffer byte size exceeded", diff); } } else ＠＠ -3197,32 +3233,10 ＠＠ { OFF_T starting; - if (FIXNUMP (start)) - { - starting = XREALFIXNUM (start); - } -#ifdef HAVE_BIGNUM - else if (bignum_fits_emacs_int_p (XBIGNUM_DATA (start))) - { - starting = bignum_to_emacs_int (XBIGNUM_DATA (start)); - } - else if (sizeof (starting) == sizeof (long long) - && bignum_fits_llong_p (XBIGNUM_DATA (start))) + if (NUMBERP (start)) { - starting = bignum_to_llong (XBIGNUM_DATA (start)); - } - else if (sizeof (starting) == sizeof (unsigned long long) - && bignum_fits_ullong_p (XBIGNUM_DATA (start))) - { - starting = bignum_to_ullong (XBIGNUM_DATA (start)); + starting = lisp_to_off_t (start); } -#endif - else - { - signal_error (Qunimplemented, - "File offset not supported in this XEmacs", - start); - } if (lseek (fd, starting, 0) < 0) report_file_error ("Setting file position", filename); ＠＠ -3424,6 +3438,7 ＠＠ Lisp_Object annotations = Qnil; struct buffer *given_buffer; Charbpos start1, end1; + OFF_T offset = 0; struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5; struct gcpro ngcpro1, ngcpro2; Lisp_Object curbuf = wrap_buffer (current_buffer); ＠＠ -3555,13 +3570,24 ＠＠ if (!NILP (append)) { - if (lseek (desc, 0, 2) < 0) + int whence = SEEK_END; + if (NUMBERP (append)) + { + whence = SEEK_SET; + offset = lisp_to_off_t (append); + if (offset < 0) + { + dead_wrong_type_argument (Qnatnump, append); + } + } + + if (lseek (desc, offset, whence) < 0) { #ifdef CLASH_DETECTION if (!auto_saving) unlock_file (lockname); #endif /* CLASH_DETECTION */ - report_file_error ("Lseek error", - filename); + report_error_with_errno (Qfile_error, "Lseek error", + list2 (filename, make_integer (offset))); } } -- ‘As I sat looking up at the Guinness ad, I could never figure out / How your man stayed up on the surfboard after forty pints of stout’ (C. Moore)