Imported Upstream version 0.8.13upstream

1 files changed, 178 insertions, 0 deletions

diff --git a/lib/checksum.c b/lib/checksum.c
new file mode 100644
index 0000000..f9e964b
--- /dev/null
+++ b/lib/checksum.c
@@ -0,0 +1,178 @@
+/*
+checksum.c - implementation of the elf{32,64}_checksum(3) functions.
+Copyright (C) 1995 - 2001 Michael Riepe
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with this library; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+*/
+
+#include <private.h>
+
+#ifndef lint
+static const char rcsid[] = "@(#) $Id: checksum.c,v 1.7 2008/05/23 08:15:34 michael Exp $";
+#endif /* lint */
+
+/*
+ * Compatibility note:
+ *
+ * The algorithm used in {elf32,elf64,gelf}_checksum() does not seem to
+ * be documented.  I hope I got it right.  My implementation does the
+ * following:
+ *
+ *   - skip sections that do not have the SHF_ALLOC flag set
+ *   - skip sections of type SHT_NULL, SHT_NOBITS, SHT_DYNSYM and
+ *     SHT_DYNAMIC
+ *   - add all data bytes from the remaining sections, modulo 2**32
+ *   - add upper and lower half of the result
+ *   - subtract 0xffff if the result is > 0xffff
+ *   - if any error occurs, return 0L
+ */
+
+static int
+skip_section(Elf_Scn *scn, unsigned cls) {
+    if (cls == ELFCLASS32) {
+	Elf32_Shdr *shdr = &scn->s_shdr32;
+
+	if (!(shdr->sh_flags & SHF_ALLOC)) {
+	    return 1;
+	}
+	switch (shdr->sh_type) {
+	    case SHT_NULL:
+	    case SHT_NOBITS:
+	    /* Solaris seems to ignore these, too */
+	    case SHT_DYNSYM:
+	    case SHT_DYNAMIC:
+		return 1;
+	}
+    }
+#if __LIBELF64
+    else if (cls == ELFCLASS64) {
+	Elf64_Shdr *shdr = &scn->s_shdr64;
+
+	if (!(shdr->sh_flags & SHF_ALLOC)) {
+	    return 1;
+	}
+	switch (shdr->sh_type) {
+	    case SHT_NULL:
+	    case SHT_NOBITS:
+	    /* Solaris seems to ignore these, too */
+	    case SHT_DYNSYM:
+	    case SHT_DYNAMIC:
+		return 1;
+	}
+    }
+#endif /* __LIBELF64 */
+    else {
+	seterr(ERROR_UNIMPLEMENTED);
+    }
+    return 0;
+}
+
+static long
+add_bytes(unsigned char *ptr, size_t len) {
+    long csum = 0;
+
+    while (len--) {
+	csum += *ptr++;
+    }
+    return csum;
+}
+
+static long
+_elf_csum(Elf *elf) {
+    long csum = 0;
+    Elf_Data *data;
+    Elf_Scn *scn;
+
+    if (!elf->e_ehdr && !_elf_cook(elf)) {
+	/* propagate errors from _elf_cook */
+	return 0L;
+    }
+    seterr(0);
+    for (scn = elf->e_scn_1; scn; scn = scn->s_link) {
+	if (scn->s_index == SHN_UNDEF || skip_section(scn, elf->e_class)) {
+	    continue;
+	}
+	data = NULL;
+	while ((data = elf_getdata(scn, data))) {
+	    if (data->d_size) {
+		if (data->d_buf == NULL) {
+		    seterr(ERROR_NULLBUF);
+		    return 0L;
+		}
+		csum += add_bytes(data->d_buf, data->d_size);
+	    }
+	}
+    }
+    if (_elf_errno) {
+	return 0L;
+    }
+    csum = (csum & 0xffff) + ((csum >> 16) & 0xffff);
+    if (csum > 0xffff) {
+	csum -= 0xffff;
+    }
+    return csum;
+}
+
+long
+elf32_checksum(Elf *elf) {
+    if (elf) {
+	if (elf->e_kind != ELF_K_ELF) {
+	    seterr(ERROR_NOTELF);
+	}
+	else if (elf->e_class != ELFCLASS32) {
+	    seterr(ERROR_CLASSMISMATCH);
+	}
+	else {
+	    return _elf_csum(elf);
+	}
+    }
+    return 0L;
+}
+
+#if __LIBELF64
+
+long
+elf64_checksum(Elf *elf) {
+    if (elf) {
+	if (elf->e_kind != ELF_K_ELF) {
+	    seterr(ERROR_NOTELF);
+	}
+	else if (elf->e_class != ELFCLASS64) {
+	    seterr(ERROR_CLASSMISMATCH);
+	}
+	else {
+	    return _elf_csum(elf);
+	}
+    }
+    return 0L;
+}
+
+long
+gelf_checksum(Elf *elf) {
+    if (elf) {
+	if (elf->e_kind != ELF_K_ELF) {
+	    seterr(ERROR_NOTELF);
+	}
+	else if (!valid_class(elf->e_class)) {
+	    seterr(ERROR_UNKNOWN_CLASS);
+	}
+	else {
+	    return _elf_csum(elf);
+	}
+    }
+    return 0L;
+}
+
+#endif /* __LIBELF64 */