zdump: refactor pt_load_add

In an upcoming patch the refactored function `pt_load_add` is reused. While at
it, add a wrap-around check to `pt_load_add`, replace `g.opts.device` access
with `fh->path` (this makes this function easier testable) and improve the
documentation.

Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdump/Makefile

@@ -44,7 +44,7 @@ all: check_dep_fuse check_dep_zlib zgetdump
 
 OBJECTS = zgetdump.o opts.o zg.o zg_error.o zg_print.o \
 	  dfi.o dfi_mem_chunk.o dfi_vmcoreinfo.o \
-	  dfi_lkcd.o dfi_elf.o \
+	  dfi_lkcd.o dfi_elf.o dfi_elf_common.o \
 	  dfi_s390.o dfi_s390_ext.o\
 	  dfi_s390mv.o dfi_s390mv_ext.o \
 	  dfi_s390tape.o dfi_kdump.o \

zdump/dfi_elf.c

@@ -24,6 +24,7 @@
 #include "df_elf.h"
 #include "dfi.h"
 #include "dfi_mem_chunk.h"
+#include "dfi_elf_common.h"
 
 /*
  * Read memory for given memory chunk
@@ -37,44 +38,6 @@ static void dfi_elf_mem_chunk_read_fn(struct dfi_mem_chunk *mem_chunk, u64 off,
 	zg_read(g.fh, buf, cnt, ZG_CHECK);
 }
 
-/*
- * Add load (memory chunk) to DFI dump
- */
-static int pt_load_add(const Elf64_Phdr *phdr)
-{
-	u64 *off_ptr;
-
-	util_log_print(UTIL_LOG_DEBUG,
-		       "DFI ELF p_paddr 0x%016lx p_vaddr 0x%016lx p_offset 0x%016lx p_filesz 0x%016lx p_memsz 0x%016lx\n",
-		       phdr->p_paddr, phdr->p_vaddr, phdr->p_offset,
-		       phdr->p_filesz, phdr->p_memsz);
-
-	if (phdr->p_paddr != phdr->p_vaddr) {
-		STDERR("Dump file \"%s\" is a user space core dump\n",
-		      g.opts.device);
-		return -EINVAL;
-	}
-	if (phdr->p_memsz == 0)
-		return -EINVAL;
-	if (phdr->p_offset + phdr->p_filesz > zg_size(g.fh))
-		return -EINVAL;
-	if (phdr->p_filesz > phdr->p_memsz)
-		return -EINVAL;
-	if (phdr->p_filesz > 0) {
-		off_ptr = zg_alloc(sizeof(*off_ptr));
-		*off_ptr = phdr->p_offset;
-		dfi_mem_chunk_add(phdr->p_paddr, phdr->p_filesz, off_ptr,
-				  dfi_elf_mem_chunk_read_fn, zg_free);
-	}
-	if (phdr->p_memsz - phdr->p_filesz > 0) {
-		/* Add zero memory chunk */
-		dfi_mem_chunk_add(phdr->p_paddr + phdr->p_filesz,
-				  phdr->p_memsz - phdr->p_filesz, NULL,
-				  dfi_mem_chunk_read_zero, NULL);
-	}
-	return 0;
-}
-
 /*
  * Ensure that CPU is already defined by prstatus note
  */
@@ -295,12 +258,17 @@ static int dfi_elf_init(void)
 
 		util_log_print(UTIL_LOG_DEBUG, "DFI ELF p_type[%d] 0x%lx\n", i, phdr->p_type);
 		switch (phdr->p_type) {
-		case PT_LOAD:
+		case PT_LOAD: {
-			if (pt_load_add(phdr)) {
+			u64 *off_ptr = zg_alloc(sizeof(*off_ptr));
+			*off_ptr = phdr->p_offset;
+
+			if (pt_load_add(g.fh, phdr, (void **)&off_ptr, dfi_elf_mem_chunk_read_fn,
+					free) < 0) {
+				free(off_ptr);
 				rc = -EINVAL;
 				goto free_phdrs;
 			}
-			break;
+		} break;
 		case PT_NOTE:
 			if (pt_notes_add(phdr)) {
 				rc = -EINVAL;

zdump/dfi_elf_common.c

@@ -0,0 +1,61 @@
+/*
+ * zgetdump - Tool for copying and converting System z dumps
+ *
+ * Common ELF core dump input format definitions
+ *
+ * Copyright IBM Corp. 2001, 2022
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include "dfi_elf_common.h"
+
+#include <assert.h>
+
+#include "lib/util_log.h"
+
+int pt_load_add(const struct zg_fh *fh, const Elf64_Phdr *phdr, void **data,
+		dfi_mem_chunk_read_fn read_fn, dfi_mem_chunk_free_fn free_fn)
+{
+	assert(fh);
+	assert(phdr);
+	assert(data);
+	assert(read_fn);
+	assert(free_fn);
+
+	util_log_print(
+		UTIL_LOG_DEBUG,
+		"%s p_paddr 0x%016lx p_vaddr 0x%016lx p_offset 0x%016lx p_filesz 0x%016lx p_memsz 0x%016lx\n",
+		__func__, phdr->p_paddr, phdr->p_vaddr, phdr->p_offset, phdr->p_filesz,
+		phdr->p_memsz);
+
+	if (phdr->p_paddr != phdr->p_vaddr) {
+		STDERR("Dump file \"%s\" is a user space core dump\n", fh->path);
+		return -EINVAL;
+	}
+	if (phdr->p_memsz == 0)
+		return -EINVAL;
+	if (phdr->p_offset + phdr->p_filesz > zg_size(fh))
+		return -EINVAL;
+	if (phdr->p_filesz > phdr->p_memsz)
+		return -EINVAL;
+	/* check for wrap-around */
+	if (phdr->p_paddr + phdr->p_filesz < phdr->p_paddr)
+		return -EINVAL;
+
+	if (phdr->p_filesz > 0) {
+		dfi_mem_chunk_add(phdr->p_paddr, phdr->p_filesz, *data, read_fn, free_fn);
+		*data = NULL;
+	} else {
+		/* Free @data directly as it's not used */
+		free_fn(*data);
+		*data = NULL;
+	}
+	if (phdr->p_memsz - phdr->p_filesz > 0) {
+		/* Add zero memory chunk */
+		dfi_mem_chunk_add(phdr->p_paddr + phdr->p_filesz, phdr->p_memsz - phdr->p_filesz,
+				  NULL, dfi_mem_chunk_read_zero, NULL);
+	}
+	return 0;
+}

zdump/dfi_elf_common.h

@@ -0,0 +1,36 @@
+/*
+ * zgetdump - Tool for copying and converting System z dumps
+ *
+ * Common ELF core dump input format definitions
+ *
+ * Copyright IBM Corp. 2001, 2022
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef DFI_ELF_COMMON_H
+#define DFI_ELF_COMMON_H
+
+#include <elf.h>
+
+#include "dfi_mem_chunk.h"
+#include "zg.h"
+
+/**
+ * pt_load_add:
+ * @fh: (not nullable): open input file
+ * @phdr: (not nullable): program ELF header of the load segment to add
+ * @data: (not nullable): arbitrary pointer passed to the read callback @read_fn
+ * @read_fn: (not nullable): callback used for reading the data of a memory chunk
+ * @free_fn: (not nullable): function called to cleanup @data
+ *
+ * Add load (memory chunk) to DFI dump. After a successful call, @data belongs
+ * to the mem_chunk structure created and the @data pointer is set to %NULL.
+ *
+ * Returns: %0 on success, returns < 0 in case of an error
+ */
+int pt_load_add(const struct zg_fh *fh, const Elf64_Phdr *phdr, void **data,
+		dfi_mem_chunk_read_fn read_fn, dfi_mem_chunk_free_fn free_fn);
+
+#endif /* DFI_ELF_COMMON_H */