$ make WERROR=-Werror now builds with -Werror

add some single char escaping routines to fmt.h
pull in html5 entities from w3c and use those to do a proper scan_html decoding
fix an off-by-one in fmt_to_array
add a ton of unit tests for the fmt routines

.cvsignore

@@ -22,3 +22,4 @@ trysendfile
 havealloca.h
 uudecode
 haveuint128.h
+ent

GNUmakefile

@@ -13,7 +13,7 @@ LIBS=byte.a fmt.a scan.a str.a uint.a open.a stralloc.a unix.a socket.a \
 buffer.a mmap.a taia.a tai.a dns.a case.a mult.a array.a io.a \
 textcode.a cdb.a
 
-all: $(LIBS) libowfat.a libsocket t
+all: ent $(LIBS) libowfat.a libsocket t
 
 CROSS=
 #CROSS=i686-mingw-
@@ -21,9 +21,13 @@ CC=$(CROSS)gcc
 CFLAGS=-pipe -W -Wall -O2 -fomit-frame-pointer
 #CFLAGS=-pipe -Os -march=pentiumpro -mcpu=pentiumpro -fomit-frame-pointer -fschedule-insns2 -Wall
 
+ent: ent.c
+	gcc -g -o ent ent.c
+
 # CFLAGS += -fstrict-aliasing -Wstrict-aliasing=2
 
-CFLAGS += -D_REENTRANT
+WERROR=
+CFLAGS += -D_REENTRANT $(WERROR)
 
 # startrip
 ifneq ($(DEBUG),)
@@ -326,3 +330,11 @@ windoze:
 
 windoze64:
 	$(MAKE) DIET= CROSS=x86_64-mingw32-
+
+update:
+	dl -n http://www.w3.org/TR/html5/entities.json
+
+entities.h: entities.json ent
+	./ent
+
+scan_html.o: entities.h

Makefile

@@ -836,3 +836,8 @@ windoze:
 
 windoze64:
 	$(MAKE) DIET= CROSS=x86_64-mingw32-
+
+entities.h: entities.json ent
+	./ent
+
+scan_html.o: entities.h

ent.c

@@ -0,0 +1,228 @@
+#include <stdio.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdlib.h>
+#include "scan.h"
+#include <assert.h>
+
+#include "scan/scan_ulong.c"
+#include "scan/scan_ulongn.c"
+#include "fmt/fmt_utf8.c"
+#include "fmt/fmt_escapecharc.c"
+
+char tmp[20];
+char tmp2[20];
+size_t n,m;
+unsigned long l;
+
+struct entity {
+  const char* entity;
+  char utf8[10];
+  struct entity* next;
+}* root,** cur=&root;
+
+struct letter {
+  char c;
+  struct letters* weiter;
+  uint32_t marshaled;	// lower 8 bits: char. rest: ofs from start of marshaled blob
+};
+
+struct letters {
+  size_t n;
+  struct letter liste[256];
+};
+
+struct letters* d;
+size_t nodes,datasize;
+
+void addword(struct letters** s,const char* t, void* pointer) {
+  size_t i;
+  if (!*s) {
+    *s=malloc(sizeof(**s));
+    memset(*s,0,sizeof(**s));
+    (*s)->liste[0].c='?';
+  }
+  i=(unsigned char)*t;
+  if ((*s)->liste[i].c==*t) {
+    if (!*t) {
+      datasize+=strlen((char*)pointer)+1;
+      (*s)->liste[i].weiter=pointer;
+    } else
+      addword(&(*s)->liste[i].weiter,t+1,pointer);
+    return;
+  }
+
+  ++nodes;
+  (*s)->n++;
+  (*s)->liste[i].c=*t;
+  if (!*t) {
+    datasize+=strlen((char*)pointer)+1;
+    (*s)->liste[i].weiter=pointer;
+  } else {
+    (*s)->liste[i].weiter=0;
+    addword(&(*s)->liste[i].weiter,t+1,pointer);
+  }
+}
+
+void dump(struct letters* s,size_t depth) {
+  size_t i,j;
+  if (!s) return;
+  for (i=0; i<256; ++i) {
+    if (s->liste[i].c!=i) continue;
+    for (j=0; j<depth; ++j) printf("  ");
+    printf("'%c' -> {\n",s->liste[i].c);
+    if (s->liste[i].c)
+      dump(s->liste[i].weiter,depth+1);
+    for (j=0; j<depth; ++j) printf("  ");
+    printf("}\n");
+  }
+}
+
+size_t used;
+size_t useddata;
+char* heap;
+uint32_t* marshaled;
+char* data;
+
+size_t marshalhelper(struct letters* s) {
+  size_t i;
+  uint32_t myindex=used;
+  if (!s) return 0;
+  used+=s->n;
+  assert(used<nodes+2);
+  for (i=1; i!=0; ++i) {	// start at 1, go to 256, then access modulo 256; effect: sort but put 0 last
+    uint32_t x;
+    i&=0xff;
+//    printf("%c ",i);
+    if (s->liste[i].c!=i) {
+      if (i==0) return;
+      continue;
+    }
+//    printf("marshalhelper: %c\n",i);
+    x=(unsigned char)s->liste[i].c;
+    if (!x) {
+      size_t l=strlen((char*)s->liste[i].weiter)+1;
+//      puts((char*)s->liste[i].weiter);
+      x|=useddata<<8;
+      assert(useddata+l<=datasize);
+      memcpy(data+useddata,s->liste[i].weiter,l);
+      useddata+=l;
+      marshaled[++myindex]=x;
+      return;
+    } else {
+      x|=(used+1)<<8;
+      marshalhelper(s->liste[i].weiter);
+    }
+    marshaled[++myindex]=x;
+  }
+//  printf("return\n");
+}
+
+void marshal(struct letters* s) {
+  fprintf(stderr,"nodes=%lu, datasize=%lu\n",nodes,datasize);
+  heap=malloc((nodes+1)*sizeof(uint32_t)+datasize);
+  if (!heap) return;
+  marshaled=(uint32_t*)heap;
+  marshaled[0]=nodes+1;
+  data=heap+(nodes+1)*sizeof(uint32_t);
+  marshalhelper(s);
+  fprintf(stderr,"actually used: %lu nodes, %lu bytes data\n",used,useddata);
+}
+
+char* lookup(char* ds,size_t ofs,const char* t) {
+  uint32_t* tab=(uint32_t*)ds;
+  if (ofs>tab[0]) return 0;
+  while (ofs<tab[0]) {
+    unsigned char ch=tab[ofs]&0xff;
+    if (ch==(unsigned char)*t) {
+      if (!ch)
+	return ds+tab[0]*sizeof(uint32_t)+(tab[ofs]>>8);
+      else
+	return lookup(ds,tab[ofs]>>8,t+1);
+    } else
+      ++ofs;
+    if (!ch) break;
+  }
+  return NULL;
+}
+
+int main() {
+  FILE* f=fopen("entities.json","r");
+  char buf[256];
+  if (!f) return 1;
+#if 0
+  puts("struct { const char* entity; const char* utf8; } codepoints[] = {");
+#endif
+  while (fgets(buf,sizeof(buf),f)) {
+    char* s,* entity;
+    size_t ul;
+    if (!isspace(buf[0])) continue;
+    for (s=buf; *s && *s!='"'; ++s) ;	// skip whitespace
+    if (!*s=='"') continue;
+    ++s;
+    entity=s;
+    if (*entity!='&') continue; ++entity; ++s;
+    for (; *s && *s!='"'; ++s) ;	// skip to end of entity
+    if (!*s=='"') continue;
+    if (s[-1]!=';') continue;
+    s[-1]=0; ++s;
+    s=strchr(s,'[');
+    if (!s) continue;
+    n=0;
+#if 0
+    printf("  { \"%s\", \"",entity);
+#endif
+    ++s;
+    *cur=malloc(sizeof(**cur));
+    (*cur)->next=0;
+    if (!((*cur)->entity=strdup(entity))) return 1;
+    ul=0;
+    do {
+      while (isspace(*s)) ++s;
+      m=scan_ulong(s,&l);
+      if (!m) return 2;
+      s+=n;
+      n=fmt_utf8(tmp,l);
+      if (ul+n>sizeof((*cur)->utf8)) return 3;
+      memcpy((*cur)->utf8+ul,tmp,n);
+      ul+=n;
+#if 0
+      {
+	size_t i;
+	for (i=0; i<n; ++i) {
+	  fwrite(tmp2,fmt_escapecharc(tmp2,(unsigned char)tmp[i]),1,stdout);
+	}
+      }
+#endif
+      if (*s==']') break;
+    } while (*s==',');
+#if 0
+    puts("\" },");
+#endif
+    addword(&d,(*cur)->entity,(*cur)->utf8);
+  }
+  fclose(f);
+//  dump(d,0);
+  marshal(d);
+  {
+    FILE* f=fopen("entities.h","w");
+    size_t i;
+    fprintf(f,"struct {\n  uint32_t tab[%lu];\n  char data[%lu];\n} entities = {\n  {",marshaled[0],datasize);
+    for (i=0; i<marshaled[0]; ++i) {
+      if (i%8 == 0) fprintf(f,"\n    ");
+      fprintf(f,"0x%x,",marshaled[i]);
+    }
+    fprintf(f,"\n  } , {");
+    for (i=0; i<datasize; ++i) {
+      if (i%16 == 0) fprintf(f,"\n    ");
+      fprintf(f,"0x%x,",data[i]&0xff);
+    }
+    fprintf(f,"\n  }\n};");
+    fclose(f);
+  }
+//  puts(lookup(heap,1,"zwnj"));
+#if 0
+  puts("};");
+#endif
+  return 0;
+}

fmt.h

@@ -145,12 +145,31 @@ size_t fmt_utf8(char* dest,uint32_t n);	/* can store 0-0x7fffffff */
 size_t fmt_asn1derlength(char* dest,unsigned long long l);	/* 0-0x7f: 1 byte, above that 1+bytes_needed bytes */
 size_t fmt_asn1dertag(char* dest,unsigned long long l);	/* 1 byte for each 7 bits; upper bit = more bytes coming */
 
-/* '&' -> '&amp;', '<' -> '&lt;'
- * 0 is rejected
- * control characters except \t \r \n are written in escaped form
- * characters from d780 to dfff and fffe and ffff and everything above 10ffff are also rejected.
- * everything else is passed through encoded as UTF-8 */
-size_t fmt_xmlescape(char* dest,uint32_t ch);
+/* Marshaling helper functions.
+ * Escape one character, no matter if it needs escaping or not.
+ * The functions will reject characters that cannot be represented but
+ * not characters that the standard says should never occur.  The idea
+ * is to make these functions useful for creating bad encoding for
+ * penetration testing.
+ * Depending on the escaping method, the input character (uint32_t, a
+ * unicode codepoint) may be limited to 0x7f, 0xff or 0x10ffff. */
+
+/* XML escaping: '&' -> '&amp;', '<' -> '&lt;', 'ö' -> '&#xf6;' */
+size_t fmt_escapecharxml(char* dest,uint32_t ch);
+/* HTML escaping is the same as XML escaping. */
+size_t fmt_escapecharhtml(char* dest,uint32_t ch);
+
+/* JSON escaping: '\' -> '\\', '"' -> '\"', 'ö' -> '\u00f6' */
+size_t fmt_escapecharjson(char* dest,uint32_t ch);
+
+/* MIME quoted-printable escaping: 'ö' -> '=f6', characters > 0xff not supported */
+size_t fmt_escapecharquotedprintable(char* dest,uint32_t ch);
+
+/* MIME quoted-printable escaping with UTF-8: 'ö' -> '=c3=b6', characters > 0x7fffffff not supported */
+size_t fmt_escapecharquotedprintableutf8(char* dest,uint32_t ch);
+
+/* C escaping: '\' -> '\\', newline -> '\n', 0xc2 -> '\302' */
+size_t fmt_escapecharc(char* dest,uint32_t ch);
 
 /* internal functions, may be independently useful */
 char fmt_tohex(char c);

fmt/fmt_escapecharc.c

@@ -0,0 +1,36 @@
+#include "fmt.h"
+
+static void fmt_oct3(char* dest,uint8_t w) {
+  dest[2]=(w&7)+'0'; w>>=3;
+  dest[1]=(w&7)+'0'; w>>=3;
+  dest[0]=(w&7)+'0';
+}
+
+size_t fmt_escapecharc(char* dest,uint32_t ch) {
+  char c;
+  if (ch>0xff) return 0;
+  switch (ch) {
+  case '\a': c='a'; goto doescape;
+  case '\b': c='b'; goto doescape;
+  case 0x1b: c='e'; goto doescape;
+  case '\f': c='f'; goto doescape;
+  case '\n': c='n'; goto doescape;
+  case '\r': c='r'; goto doescape;
+  case '\t': c='t'; goto doescape;
+  case '\v': c='v'; goto doescape;
+  case '\\':
+    c='\\';
+  doescape:
+    if (dest) {
+      dest[0]='\\';
+      dest[1]=c;
+    }
+    return 2;
+  default:
+    if (dest) {
+      dest[0]='\\';
+      fmt_oct3(dest+1,ch&0xff);
+    }
+    return 4;
+  }
+}

fmt/fmt_escapecharhtml.c

@@ -0,0 +1,9 @@
+#ifndef __GNUC__
+
+#include "fmt.h"
+
+size_t fmt_escapecharhtml(char* dest,uint32_t ch) {
+  return fmt_escapecharxml(dest,ch);
+}
+
+#endif

fmt/fmt_escapecharjson.c

@@ -0,0 +1,47 @@
+#include "fmt.h"
+
+static void fmt_hex4(char* dest,uint16_t w) {
+  dest[3]=fmt_tohex(w&0xf); w>>=4;
+  dest[2]=fmt_tohex(w&0xf); w>>=4;
+  dest[1]=fmt_tohex(w&0xf); w>>=4;
+  dest[0]=fmt_tohex(w&0xf);
+}
+
+size_t fmt_escapecharjson(char* dest,uint32_t ch) {
+  size_t n;
+  switch (ch) {
+  case '\b':
+    ch='b'; goto simple;
+  case '\n':
+    ch='n'; goto simple;
+  case '\r':
+    ch='r'; goto simple;
+  case '"':
+  case '\\':
+  case '/':
+simple:
+    if (dest) {
+      dest[0]='\\';
+      dest[1]=ch;
+    }
+    return 2;
+  }
+  if (ch>0xffff) {
+    if (ch>0x10ffff) return 0;	// highest representable unicode codepoint
+    if (dest) {
+      dest[0]='\\';
+      dest[1]='u';
+      fmt_hex4(dest+2,0xd800 | (((ch-0x10000)>>10)&0x3ff));
+      dest+=6;
+    }
+    ch=(ch&0x3ff)|0xdc00;
+    n=6;
+  } else
+    n=0;
+  if (dest) {
+    dest[0]='\\';
+    dest[1]='u';
+    fmt_hex4(dest+2,ch);
+  }
+  return n+6;
+}

fmt/fmt_escapecharquotedprintable.c

@@ -0,0 +1,11 @@
+#include "fmt.h"
+
+size_t fmt_escapecharquotedprintable(char* dest,uint32_t ch) {
+  if (ch>0xff) return 0;
+  if (dest) {
+    dest[0]='=';
+    dest[2]=fmt_tohex(ch&0xf); ch>>=4;
+    dest[1]=fmt_tohex(ch&0xf);
+  }
+  return 3;
+}

fmt/fmt_escapecharquotedprintableutf8.c

@@ -0,0 +1,10 @@
+#include "fmt.h"
+
+size_t fmt_escapecharquotedprintableutf8(char* dest,uint32_t ch) {
+  char buf[FMT_UTF8];
+  size_t i,o,j=fmt_utf8(buf,ch);
+  if (!dest) return j*3;
+  for (i=o=0; i<j; ++i)
+    o+=fmt_escapecharquotedprintable(dest+o,(unsigned char)buf[i]);
+  return o;
+}

fmt/fmt_escapecharxml.c

@@ -0,0 +1,33 @@
+#include "fmt.h"
+
+size_t fmt_escapecharxml(char* dest,uint32_t ch) {
+  char a[FMT_LONG], b[FMT_XLONG];
+  const char* s;
+  size_t i,j;
+  switch (ch) {
+  case '&': s="&"; goto string;
+  case '<': s="&lt;"; goto string;
+  case '>': s="&gt;"; goto string;
+  case '\'': s="&apos;"; goto string;
+  case '"': s="&quot;"; goto string;
+  default:
+    a[i=fmt_ulong(a,ch)]=0;
+    b[0]='x';
+    b[j=fmt_xlong(b+1,ch)+1]=0;
+    s=a;
+    if (i>j) { s=b; i=j; }
+    if (dest) {
+      dest[0]='&';
+      dest[1]='#';
+      byte_copy(dest+2,i,s);
+      dest[i+2]=';';
+    }
+    return i+3;
+  }
+string:
+  return fmt_str(dest,s);
+}
+
+#ifdef __GNUC__
+size_t fmt_escapecharhtml(char* dest,uint32_t ch) __attribute__((__alias__("fmt_escapecharxml")));
+#endif

test/marshal.c

@@ -104,4 +104,28 @@ int main() {
   zap(); assert(fmt_asn1dertag(buf,0xc2)==2 && byte_equal(buf,3,"\x81\x42_"));
 
   zap(); assert(fmt_strm(buf,"hell","o, worl","d!\n")==14 && byte_equal(buf,15,"hello, world!\n_"));
+
+  assert(fmt_escapecharxml(NULL,0xc2)==6);
+  zap(); assert(fmt_escapecharxml(buf,0xc2)==6 && byte_equal(buf,7,"Â_"));
+  assert(fmt_escapecharxml(NULL,0)==4);
+  zap(); assert(fmt_escapecharxml(buf,0)==4 && byte_equal(buf,5,"�_"));
+
+  assert(fmt_escapecharjson(NULL,'\\')==2);	// "\\"
+  zap(); assert(fmt_escapecharjson(buf,'\\')==2 && byte_equal(buf,3,"\\\\_"));
+  assert(fmt_escapecharjson(NULL,0xc2)==6);	// "\u00c2"
+  zap(); assert(fmt_escapecharjson(buf,0xc2)==6 && byte_equal(buf,7,"\\u00c2_"));
+  assert(fmt_escapecharjson(NULL,0x1d11e)==12);	// "\ud834\xdd1e"
+  zap(); assert(fmt_escapecharjson(buf,0x1d11e)==12 && byte_equal(buf,13,"\\ud834\\udd1e_"));
+
+  assert(fmt_escapecharquotedprintable(NULL,'=')==3);	// =3d
+  zap(); assert(fmt_escapecharquotedprintable(buf,'=')==3 && byte_equal(buf,4,"=3d_"));
+  assert(fmt_escapecharquotedprintable(NULL,0xf6)==3);	// =f6
+  zap(); assert(fmt_escapecharquotedprintable(buf,0xf6)==3 && byte_equal(buf,4,"=f6_"));
+  assert(fmt_escapecharquotedprintable(NULL,0x100)==0);
+
+  assert(fmt_escapecharquotedprintableutf8(NULL,'=')==3);	// =3d
+  zap(); assert(fmt_escapecharquotedprintableutf8(buf,'=')==3 && byte_equal(buf,4,"=3d_"));
+  assert(fmt_escapecharquotedprintableutf8(NULL,0xf6)==6);	// =c3=b6
+  zap(); assert(fmt_escapecharquotedprintableutf8(buf,0xf6)==6 && byte_equal(buf,7,"=c3=b6_"));
+
 }

test/textcode.c

@@ -19,5 +19,12 @@ int main() {
   assert(!array_failed(&a));
   write(1,array_start(&a),array_bytes(&a)); write(1,"\n",1);
   array_trunc(&a);
+
+  strcpy(buf,"Ächt fnördig.");
+  size_t n;
+  scan_html(buf,buf,&n);
+  buf[n]=0;
+  puts(buf);
+
   return 0;
 }

textcode/fmt_to_array.c

@@ -4,7 +4,7 @@
 void fmt_to_array(size_t (*func)(char*,const char*,size_t),
 		  array* a,const char* src,size_t len) {
   size_t needed=func(0,src,len);
-  if (array_bytes(a)+needed>needed &&
+  if (array_bytes(a)+needed>=needed &&
       array_allocate(a,1,array_bytes(a)+needed-1)) {
     char* x=((char*)array_start(a))+array_bytes(a)-needed;
     func(x,src,len);

textcode/scan_html.c

@@ -1,23 +1,63 @@
+#include <inttypes.h>
+#include <string.h>
+#include "entities.h"
+
 #include "fmt.h"
 #include "textcode.h"
 #include "haveinline.h"
+#include "scan.h"
 #include "case.h"
+#include "str.h"
+
+static const char* lookup(size_t ofs,const char* t) {
+  if (ofs>entities.tab[0]) return 0;
+  while (ofs<entities.tab[0]) {
+    unsigned char ch=entities.tab[ofs]&0xff;
+    if (ch==(unsigned char)*t || (!ch && *t==';')) {
+      if (!ch || *t==';')
+	return entities.data+(entities.tab[ofs]>>8);
+      else
+	return lookup(entities.tab[ofs]>>8,t+1);
+    } else
+      ++ofs;
+    if (!ch) break;
+  }
+  return NULL;
+}
 
 size_t scan_html(const char *src,char *dest,size_t *destlen) {
   register const unsigned char* s=(const unsigned char*) src;
   size_t written=0,i;
   for (i=0; s[i]; ++i) {
     if (s[i]=='&') {
-      if (case_starts((const char*)s+i+1,"amp;")) {
-	dest[written]='&';
-	i+=4;
-      } else if (case_starts((const char*)s+i+1,"lt;")) {
-	dest[written]='<';
-	i+=3;
-      } else if (case_starts((const char*)s+i+1,"gt;")) {
-	dest[written]='>';
-	i+=3;
+      const char* utf8;
+      if (s[i+1]=='#') {
+	unsigned long l;
+	size_t j;
+	if ((s[i+2]&~32)=='X') {
+	  j=scan_xlong(src+i+3,&l);
+	  if (!j) j+=3;
+	} else {
+	  j=scan_ulong(src+i+2,&l);
+	  if (!j) j+=3;
+	}
+	if (s[i+j]==';') {
+	  i+=j;
+	  written+=fmt_utf8(dest+written,l);
+	} else {
+	  dest[written++]='&';
+	}
+	continue;
       }
+      utf8=lookup(1,src+i+1);
+      if (utf8) {
+	size_t l=strlen(utf8);
+	memcpy(dest+written,utf8,l);
+	written+=l;
+	i+=2+str_chr(src+i+2,';');
+	continue;
+      } else
+	dest[written]='&';
     } else if (s[i]=='<') {
       if (case_starts((const char*)s+i+1,"br>")) {
 	dest[written]='\n';

tryalloca.c

@@ -5,6 +5,8 @@
 #include <malloc.h>
 #endif
 
-main() {
+int main() {
   char* c=alloca(23);
+  (void)c;
+  return 0;
 }

trybsdsf.c

@@ -16,4 +16,6 @@ int main() {
   hdr.headers=v; hdr.hdr_cnt=17;
   hdr.trailers=v+17; hdr.trl_cnt=23;
   r=sendfile(0,1,37,42,&hdr,&sbytes,0);
+  (void)r;
+  return 0;
 }

tryepoll.c

@@ -1,5 +1,6 @@
 #include <inttypes.h>
 #include <sys/epoll.h>
+#include <stdio.h>
 
 int main() {
   int efd=epoll_create(10);
@@ -9,10 +10,11 @@ int main() {
   x.data.fd=0;
   if (epoll_ctl(efd,EPOLL_CTL_ADD,0 /* fd */,&x)==-1) return 111;
   {
-    int i,n;
+    int n;
     struct epoll_event y[100];
     if ((n=epoll_wait(efd,y,100,1000))==-1) return 111;
     if (n>0)
       printf("event %d on fd #%d\n",y[0].events,y[0].data.fd);
   }
+  return 0;
 }

tryip6.c

@@ -2,7 +2,9 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 
-main() {
+int main() {
   struct sockaddr_in6 sa;
   sa.sin6_family = PF_INET6;
+  (void)sa;
+  return 0;
 }

tryn2i.c

@@ -5,4 +5,6 @@
 int main() {
   static char ifname[IFNAMSIZ];
   char *tmp=if_indextoname(0,ifname);
+  (void)tmp;
+  return 0;
 }

tryscope.c

@@ -2,8 +2,10 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 
-main() {
+int main() {
   struct sockaddr_in6 sa;
   sa.sin6_family = PF_INET6;
   sa.sin6_scope_id = 23;
+  (void)sa;
+  return 0;
 }

trysendfile.c

@@ -55,6 +55,7 @@ int main() {
   p.trailer_length=6;
   if (send_file(&destfd,&p,0)>=0)
     printf("sent %lu bytes.\n",p.bytes_sent);
+  return 0;
 }
 #elif defined(__linux__)
 
@@ -77,6 +78,7 @@ int main() {
   off_t r=sendfile(1,fd,&o,23);
   if (r!=-1)
     printf("sent %llu bytes.\n",r);
+  return 0;
 }
 
 #else

trysigio.c

@@ -3,6 +3,7 @@
 #include <sys/poll.h>
 #include <signal.h>
 #include <fcntl.h>
+#include <stdio.h>
 
 int main() {
   int signum=SIGRTMIN+1;
@@ -36,4 +37,5 @@ int main() {
       }
     }
   }
+  return 0;
 }

trysl.c

@@ -7,6 +7,8 @@
 #include <netinet/in.h>
 #endif
 
-main() {
+int main() {
   socklen_t t;
+  (void)t;
+  return 0;
 }

trysocket.c

@@ -2,6 +2,8 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 
-main() {
+int main() {
   int fd=socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
+  (int)fd;
+  return 0;
 }