dos/com and dos/sys: only add the `sbb bp,bp' section to the stub

if it is needed.

committer: mfx <mfx> 978538864 +0000

TODO

@@ -1,4 +1,4 @@
-UPX TODO list. Last updated 2000-12-29.
+UPX TODO list. Last updated 2001-01-03.
 
 
 
@@ -26,7 +26,7 @@ ALL FORMATS
 - implement `--cpu=486' option to use bswap on the 32-bit formats
     (if cpu >= 486)
 
-- consider removing "sbb bp,bp" or "or ebp,-1" when not needed
+- consider removing "or ebp,-1" when not needed
 
 
 FORMAT DJGPP2/COFF

src/p_com.cpp

@@ -118,7 +118,7 @@ void PackCom::patchLoader(OutputFile *fo,
 
     // NOTE: Depends on: decompr_start == cutpoint+1 !!!
     patch_le16(loader,e_len,"JM",upper_end - 0xff - d_len - getLoaderSection("UPX1HEAD"));
-    loader[getLoaderSection("COMSUBSI") - 1] = (upx_byte) -e_len;
+    loader[getLoaderSectionStart("COMSUBSI") - 1] = (upx_byte) -e_len;
     patch_le16(loader,e_len,"DI",upper_end);
     patch_le16(loader,e_len,"SI",ph.c_len + lsize + 0x100);
     patch_le16(loader,e_len,"CX",ph.c_len + lsize);
@@ -141,6 +141,8 @@ int PackCom::buildLoader(const Filter *ft)
     const int filter_id = ft->id;
     initLoader(nrv2b_loader,sizeof(nrv2b_loader));
     addLoader("COMMAIN1""COMSUBSI",
+              ph.first_offset_found == 1 ? "COMSBBBP" : "",
+              "COMPSHDI",
               filter_id ? "COMCALLT" : "",
               "COMMAIN2""UPX1HEAD""COMCUTPO""NRV2B160",
               filter_id ? "NRVDDONE" : "NRVDRETU",

src/p_sys.cpp

@@ -91,7 +91,7 @@ void PackSys::patchLoader(OutputFile *fo,
 
     const unsigned jmp_pos = find_le16(loader,e_len,get_le16("JM"));
     patch_le16(loader,e_len,"JM",ph.u_len+ph.overlap_overhead+2-jmp_pos-2);
-    loader[getLoaderSection("SYSSUBSI") - 1] = (upx_byte) -e_len;
+    loader[getLoaderSectionStart("SYSSUBSI") - 1] = (upx_byte) -e_len;
     patch_le16(loader,e_len,"DI",copy_to);
     patch_le16(loader,e_len,"SI",ph.c_len+e_len+d_len-1);
 
@@ -109,6 +109,7 @@ int PackSys::buildLoader(const Filter *ft)
     addLoader("SYSMAIN1",
               opt->cpu == opt->CPU_8086 ? "SYSI0861" : "SYSI2861",
               "SYSMAIN2""SYSSUBSI",
+              ph.first_offset_found == 1 ? "SYSSBBBP" : "",
               filter_id ? "SYSCALLT" : "",
               "SYSMAIN3""UPX1HEAD""SYSCUTPO""NRV2B160""NRVDDONE""NRVDECO1",
               ph.max_offset_found <= 0xd00 ? "NRVLED00" : "NRVGTD00",

src/stub/l_com.asm

@@ -59,7 +59,9 @@ mem_ok:
                 xchg    si, di
                 sub     si, byte start - cutpoint
 ;       __COMSUBSI__
+;       __COMSBBBP__
                 sbb     bp, bp
+;       __COMPSHDI__
                 push    di
 %ifdef  __COMCALLT__
                 push    di

src/stub/l_sys.asm

@@ -78,6 +78,7 @@ strategy:
                 xchg    si, di
                 sub     si, byte start - cutpoint
 ;       __SYSSUBSI__
+;       __SYSSBBBP__
                 sbb     bp, bp
 %ifdef  __SYSCALLT__
                 push    di