Implement compression/decompression of filenames ending .gz

src/sysfiles.c

@@ -616,6 +616,9 @@ Int SyFopen (
     Char                namegz [1024];
     int                 flags = 0;
 
+    Char* terminator = strrchr(name, '.');
+    Int endsgz = terminator && (strcmp(terminator, ".gz") == 0);
+
     /* handle standard files                                               */
     if ( strcmp( name, "*stdin*" ) == 0 ) {
         if ( strcmp( mode, "r" ) != 0 )
@@ -677,8 +680,11 @@ Int SyFopen (
 #endif
 
     /* try to open the file                                                */
-    syBuf[fid].fp = open(name,flags, 0644);
-    if ( 0 <= syBuf[fid].fp ) {
+    if (endsgz && (syBuf[fid].gzfp = gzopen(name, mode))) {
+        syBuf[fid].type = gzip_socket;
+        syBuf[fid].fp = -1;
+        syBuf[fid].bufno = -1;
+    } else if (0 <= (syBuf[fid].fp = open(name, flags, 0644))) {
         syBuf[fid].type = raw_socket;
         syBuf[fid].echo = syBuf[fid].fp;
         syBuf[fid].bufno = -1;

tst/example-dir/compress/not-compressed.txt.gz

@@ -0,0 +1 @@
+not compressed

tst/example-dir/readme.txt

@@ -7,3 +7,5 @@ Explanation
 
 dir-test : A directory containing some example files and sub-directories
            for testing directory enumeration.
+
+compress : not-compressed.txt - A text file which is not compressed but ends in gz

tst/testinstall/compressed.tst

@@ -0,0 +1,169 @@
+#@local dir,fname,isGzippedFile,stream,str
+gap> START_TEST("compressed.tst");
+gap> dir := DirectoryTemporary();;
+gap> fname := Filename(dir, "test.g.gz");;
+
+# Let us check when we have written a compressed file by checking the gzip header
+gap> isGzippedFile := function(dir, name)
+>    local out, str,prog;
+>    str := "";
+>    out := OutputTextString(str, true);
+>    Process(dir, Filename(DirectoriesSystemPrograms(),"cat"), InputTextNone(), out, [name]);
+>    return str{[1..2]} = "\037\213";
+>  end;;
+gap> str := "hello\ngoodbye\n";;
+
+# Write a compressed file
+gap> FileString( fname, str ) = Length(str);
+true
+
+# Check file really is compressed
+gap> isGzippedFile(dir, "test.g.gz");
+true
+
+# Check reading compressed file
+gap> StringFile( fname ) = str;
+true
+
+# Check gz is added transparently
+gap> StringFile( Filename(dir, "test.g") ) = str;
+true
+
+# Test reading/seeking in a gzip compressed file
+gap> stream := InputTextFile(fname);;
+gap> ReadLine(stream);
+"hello\n"
+gap> ReadLine(stream);
+"goodbye\n"
+gap> ReadLine(stream);
+fail
+gap> SeekPositionStream(stream, -1);
+fail
+gap> SeekPositionStream(stream, 0);
+true
+gap> ReadLine(stream);
+"hello\n"
+gap> ReadLine(stream);
+"goodbye\n"
+gap> ReadLine(stream);
+fail
+gap> SeekPositionStream(stream, 2);
+true
+gap> PositionStream(stream);
+2
+gap> ReadLine(stream);
+"llo\n"
+gap> ReadLine(stream);
+"goodbye\n"
+gap> SeekPositionStream(stream, 0);
+true
+gap> ReadAll(stream) = str;
+true
+gap> SeekPositionStream(stream, 0);
+true
+gap> PositionStream(stream);
+0
+gap> ReadAll(stream) = str;
+true
+gap> CloseStream(stream);
+
+# Test multiple writes
+gap> stream := OutputTextFile( fname, false );;
+gap> PrintTo( stream, "1");
+gap> AppendTo( stream, "2");
+gap> PrintTo( stream, "3");
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+gap> isGzippedFile(dir, "test.g.gz");
+true
+
+# verify it
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream);
+"123"
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+
+# partial reads
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream, 2);
+"12"
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+
+# too long partial read
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream, 5);
+"123"
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+
+# error partial read
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream, -1);
+Error, ReadAll: negative limit is not allowed
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+
+# append to initial data
+gap> stream := OutputTextFile( fname, true );;
+gap> PrintTo( stream, "4");
+gap> CloseStream(stream);
+
+# verify it
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream);
+"1234"
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+
+# overwrite initial data
+gap> stream := OutputTextFile( fname, false );;
+gap> PrintTo( stream, "new content");
+gap> CloseStream(stream);
+
+# verify it
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream);
+"new content"
+gap> CloseStream(stream);
+gap> stream;
+closed-stream
+
+# ReadAll with length limit
+gap> stream := InputTextFile( fname );;
+gap> ReadAll(stream, 3);
+"new"
+gap> CloseStream(stream);
+
+# test PrintFormattingStatus
+gap> stream := OutputTextFile( fname, false );;
+gap> PrintFormattingStatus(stream);
+true
+gap> PrintTo( stream, "a very long line that GAP is going to wrap at 80 chars by default if we don't do anything about it\n");
+gap> CloseStream(stream);
+gap> StringFile(fname);
+"a very long line that GAP is going to wrap at 80 chars by default if we don't\
+ \\\ndo anything about it\n"
+gap> stream := OutputTextFile( fname, false );;
+gap> SetPrintFormattingStatus(stream, false);
+gap> PrintFormattingStatus(stream);
+false
+gap> PrintTo( stream, "a very long line that GAP is going to wrap at 80 chars by default if we don't do anything about it\n");
+gap> CloseStream(stream);
+gap> StringFile(fname);
+"a very long line that GAP is going to wrap at 80 chars by default if we don't\
+ do anything about it\n"
+
+# Test even if a file ends in .gz, if it is not compressed it can still be read
+gap> stream := InputTextFile(Filename(DirectoriesLibrary("tst"), "example-dir/compress/not-compressed.txt.gz"));;
+gap> ReadAll(stream) = "not compressed\n";
+true
+gap> CloseStream(stream);
+gap> STOP_TEST("compressed.tst");

tst/testinstall/read.tst

@@ -75,10 +75,6 @@ gap> StringFile( Filename(dir, "tmp2"));
 fail
 gap> StringFile( Filename(dir, "tmp1"));
 "Hello, world!"
-gap> FileString( Filename(dir, "test.g.gz"), "\037\213\b\b0,\362W\000\ctest.g\0003\3246\264\346\<\000\225\307\236\324\005\000\000\000" );
-32
-gap> StringFile( Filename(dir, "test.g") ) = "1+1;\n" or ARCH_IS_WINDOWS(); # works only when Cygwin installed with gzip
-true
 gap> StringFile( "/" );
 Error, in StringFile: Is a directory (21)