scripts/faddr2line: Fix "Argument list too long" error

The run_readelf() function reads the entire output of readelf into a
single shell variable. For large object files with extensive debug
information, the size of this variable can exceed the system's
command-line argument length limit.

When this variable is subsequently passed to sed via `echo "${out}"`, it
triggers an "Argument list too long" error, causing the script to fail.

Fix this by redirecting the output of readelf to a temporary file
instead of a variable. The sed commands are then modified to read from
this file, avoiding the argument length limitation entirely.

Signed-off-by: Pankaj Raghav <[e-mail]>
Signed-off-by: Josh Poimboeuf <[e-mail]>

scripts/faddr2line

···
 
 run_readelf() {
 	local objfile=$1
-	local out=$(${READELF} --file-header --section-headers --symbols --wide $objfile)
+	local tmpfile
+	tmpfile=$(mktemp)
+
+	${READELF} --file-header --section-headers --symbols --wide "$objfile" > "$tmpfile"
 
 	# This assumes that readelf first prints the file header, then the section headers, then the symbols.
 	# Note: It seems that GNU readelf does not prefix section headers with the "There are X section headers"
 	# line when multiple options are given, so let's also match with the "Section Headers:" line.
-	ELF_FILEHEADER=$(echo "${out}" | sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/q;p')
-	ELF_SECHEADERS=$(echo "${out}" | sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/,$p' | sed -n '/Symbol table .* contains [0-9]* entries:/q;p')
-	ELF_SYMS=$(echo "${out}" | sed -n '/Symbol table .* contains [0-9]* entries:/,$p')
+	ELF_FILEHEADER=$(sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/q;p' "$tmpfile")
+	ELF_SECHEADERS=$(sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/,$p' "$tmpfile" | sed -n '/Symbol table .* contains [0-9]* entries:/q;p')
+	ELF_SYMS=$(sed -n '/Symbol table .* contains [0-9]* entries:/,$p' "$tmpfile")
+
+	rm -f -- "$tmpfile"
 }
 
 check_vmlinux() {