Make pbm_readpbminit() and pgm_readpgminit() recognize other Netpbm formats and issue special error message

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@410 9d0c8265-081b-0410-96cb-a4ca84ce46f8

3 files changed, 49 insertions, 23 deletions

diff --git a/doc/HISTORY b/doc/HISTORY
index d8b62dcf..1b16f17e 100644
--- a/doc/HISTORY
+++ b/doc/HISTORY
@@ -29,7 +29,7 @@ not yet  BJH  Release 10.40.00
               sample Postscript.  It doesn't really know how to do that, so
               now it just writes 8 unless you do -psfilter.
 
-              pnmmargin: recognize invalid options better.    Thanks
+              pnmmargin: recognize invalid options better.  Thanks
               Prophet of the Way <afu@wta.att.ne.jp>.
 
               pnmtopng: Sort palette properly when alpha maxval != 255.
@@ -42,6 +42,10 @@ not yet  BJH  Release 10.40.00
 
               libnetpbm: Add pm_system_lp(), pm_system_vp().
 
+              libnetpbm: Make pbm_readpbminit() and pgm_readpgminit()
+              recognize incompatible Netpbm formats and issue a
+              helpful error message.
+
               libnetpbm: pbm_readppminit: read PBM as maxval of 255, not 1.
 
               libnetpbm: Fix pm_drain() to use the specified limit.
diff --git a/lib/libpbm2.c b/lib/libpbm2.c
index d04328ef..19ca93b3 100644
--- a/lib/libpbm2.c
+++ b/lib/libpbm2.c
@@ -13,6 +13,7 @@
 #include "pbm.h"
 #include "libpbm.h"
 #include "fileio.h"
+#include "pam.h"
 
 static bit 
 getbit (FILE * const file) {
@@ -54,25 +55,42 @@ pbm_readpbminitrest( file, colsP, rowsP )
         pm_error("Number of columns in header is too large.");
     }
 
-void
-pbm_readpbminit( file, colsP, rowsP, formatP )
-    FILE* file;
-    int* colsP;
-    int* rowsP;
-    int* formatP;
-    {
-    /* Check magic number. */
-    *formatP = pm_readmagicnumber( file );
-    switch ( PBM_FORMAT_TYPE(*formatP) )
-    {
-        case PBM_TYPE:
-    pbm_readpbminitrest( file, colsP, rowsP );
-    break;
 
+
+void
+pbm_readpbminit(FILE * const ifP,
+                int *  const colsP,
+                int *  const rowsP,
+                int *  const formatP) {
+
+    *formatP = pm_readmagicnumber(ifP);
+
+    switch (PAM_FORMAT_TYPE(*formatP)) {
+    case PBM_TYPE:
+        pbm_readpbminitrest(ifP, colsP, rowsP);
+        break;
+
+    case PGM_TYPE:
+        pm_error("The input file is a PGM, not a PBM.  You may want to "
+                 "convert it to PBM with 'pamditherbw | pamtopnm' or "
+                 "'pamthreshold | pamtopnm'");
+
+    case PPM_TYPE:
+        pm_error("The input file is a PPM, not a PBM.  You may want to "
+                 "convert it to PBM with 'ppmtopgm', 'pamditherbw', and "
+                 "'pamtopnm'");
+
+    case PAM_TYPE:
+        pm_error("The input file is a PAM, not a PBM.  "
+                 "If it is a black and white image, you can convert it "
+                 "to PBM with 'pamtopnm'");
+        break;
     default:
-    pm_error( "bad magic number - not a pbm file" );
-    }
+        pm_error("bad magic number - not a Netpbm file");
     }
+}
+
+
 
 void
 pbm_readpbmrow( file, bitrow, cols, format )
diff --git a/lib/libpgm1.c b/lib/libpgm1.c
index f615069d..34cc6392 100644
--- a/lib/libpgm1.c
+++ b/lib/libpgm1.c
@@ -122,11 +122,6 @@ pgm_readpgminit(FILE * const fileP,
     /* Check magic number. */
     realFormat = pm_readmagicnumber(fileP);
     switch (PAM_FORMAT_TYPE(realFormat)) {
-    case PGM_TYPE:
-        *formatP = realFormat;
-        pgm_readpgminitrest(fileP, colsP, rowsP, maxvalP);
-        break;
-        
     case PBM_TYPE:
         *formatP = realFormat;
         pbm_readpbminitrest(fileP, colsP, rowsP);
@@ -150,6 +145,15 @@ pgm_readpgminit(FILE * const fileP,
         *maxvalP = PGM_MAXMAXVAL;
         break;
 
+    case PGM_TYPE:
+        *formatP = realFormat;
+        pgm_readpgminitrest(fileP, colsP, rowsP, maxvalP);
+        break;
+        
+    case PPM_TYPE:
+        pm_error("Input file is a PPM, which this program cannot process.  "
+                 "You may want to convert it to PGM with 'ppmtopgm'");
+
     case PAM_TYPE:
         pnm_readpaminitrestaspnm(fileP, colsP, rowsP, maxvalP, formatP);
 
@@ -159,7 +163,7 @@ pgm_readpgminit(FILE * const fileP,
         break;
 
     default:
-        pm_error("bad magic number - not a pgm or pbm file");
+        pm_error("bad magic number - not a Netpbm file");
     }
     validateComputableSize(*colsP, *rowsP);
 }